Hi Aussie,
Welcome from the land down under 
While Iām certainly not nearly as familiar with the different market, measurements (metric), currency, brands, and names that are used there as I am with the North American equivalents, the basic ideas of finding a better quality mattress and better value would be the same in all places.
Some guidelines that would help people in most areas to avoid the traps and pitfalls of mattress shipping are here.
One of the most challenging things in reading reviews is that so many of them are really talking about the wisdom of the choice someone made rather than the quality of the mattress they ended up choosing. Many are written soon after the purchase and say ādonāt buy this brandā or āthat brandā without even mentioning the specific mattress they purchased, or the materials in the mattress which is what should be reviewed. Even the best quality most expensive mattress can be a poor choice for any individual if the mattress is not designed for their height, weight, body shape, sleeping positions, and preferences. In addition to this, all mattresses are only as good as the material in it and the methods used in itās construction and without knowing these and the āweak linkā that can fail first ā¦ knowing the brand label that is attached to it has very little value.
Warranties are also a very misleading indicator of the quality of a mattress and the warranty exclusions will often say more than the warranty itself. Warranties only cover construction defects and donāt cover the wear and tear or softening of a mattress so if a mattress has a 25 year warranty and wears out in 3 years ā¦ it is not covered. In addition to this ā¦ if a mattress has a stain, isnāt on what the manufacturer considers to be a suitable foundation, or any other āexclusionā is evident ā¦ the warranty is also voided. Each warranty has a different ādefinitionā of what normal wear and tear is in terms of a body impression (how deep an impression is considered ānormalā with no weight on the mattress) and because most mattresses will soften (or in some cases any fibers used on the surface will compress and become too firm) to the point of being unsuitable for sleeping on long before unweighted impressions that are deeper than the exclusion develop ā¦ warranties are mostly useless. Because of this ā¦ warranties are more of a sales tool used to justify āstepping someone upā to a mattress that is higher priced. Once again ā¦ knowing the specifics of the materials in a mattress is the only real way to know the quality and durability of a mattress in practical terms.
This is also why choosing an outlet that knows about mattress components and materials and helps to āeducateā their customers without regard to brand and will tell their customers about the specifics of the materials in their mattresses is usually the most important first step in buying a mattress. Transparency and materials knowledge, and the ability and willingness to fit a mattress to a customer based on Pressure relief, Posture and alignment, and Preferences rather than encouraging a customer to buy based on vague descriptions or ideas of ācomfortā are the way to tell better outlets from worse ones.
A quick read of the overviews in the mattresses section of the site will provide a good level of general information about materials, construction, and fitting a mattress to a person and will help people ask better questions while they are shopping (and help them know who really knows what they are talking about). āStudyingā these isnāt nearly as important as just getting a general picture of what is important.
In general ā¦ a mattress should be chosen first on itās ability to provide good sleeping posture and spinal alignment while fully relaxed in all your sleeping positions. Posture is the first key part of healthy sleeping (and healthy sleeping is always the most comfortable in the long term outside of the showroom)
Secondly ā¦ a mattress should be chosen on its ability to spread your body weight throughout the mattress surface and relieve pressure to allow for good circulation in all your sleeping positions. Pressure relief is the second key part of healthy sleeping.
Finally ā¦ a mattress that provides good Posture and Pressure relief should also include your preferences. These include the sleeping microclimate and temperature control, ease of movement on the mattress and the overall feel of the mattress. These preferences are the final part of healthy sleeping because a mattress that is too hot or that doesnāt allow for your natural movement or position changes or in other ways āannoysā a sleeper will also not allow for the deepest possible healthy sleep.
Buying a mattress from a āsalespersonā who sells comfort alone based on the managed and subjective perceptions on a showroom floor is always a warning sign. A mattress salesperson should be selling Posture, Pressure relief, and Preferences (and know how to tell the difference) and then show a customer the materials in the mattress that provides these so that a meaningful comparison can be made with other mattresses based on āvalueā and on the durability of the materials inside the mattress.
Just to ātranslateā this into NA terms for those who may be following this (and to give me a reference instead of translating it each time) ā¦ 75 kg is 165 lbs and 55 kg is 121 lbs. Weight is one of the āgeneralā factors that can be helpful as a starting point in matching a person to a mattress but by itself it is only a small part of the āspecsā that can make a difference. Height, body shape, and weight distribution are also important along with sleeping positions, flexibility, overall health, sensitivity to pressure, various sleeping positions, and environment, overall health, what someone is used to or the ābody memoryā from a previous mattress, and natural variations in each persons makeup are also important factors. There are so many variables that a personās āspecsā are generally useful as guidelines or starting points only and the experience of actually testing a mattress in āreal lifeā is always the most accurate way to āmatchā a mattress to a person. This is why testing for PPP (Pressure relief, Posture, and Preferences) is so important and also why when buying online without personal testing that the exchange or return policy of the outlet you buy from is so important.
Pocket springs can be a great choice for a support system but like all materials they will come in a wide variety of choices that can be firmer or softer or more or less aligning for different people. They are also a support system and the materials that are on top of the pocket springs (the comfort layers) have as much to do with the qualities of the mattress as the pocket springs themselves. There are also different types of latex and it comes in a very wide range of firmness/softness levels so there are many types of ālatex mattressesā that can be matched to an individualās needs and preferences. It can be used as a support material in the firmer versions and as a comfort layer in the softer versions. Itās also important to remember that what many outlets call a ālatex mattressā really isnāt and will only contain a thin layer of latex mixed in with other materials.
Having said all that ā¦ each material or component used in either a support system or comfort layer tends to have a general feel which is a matter of preference and there is no āright or wrongā here. In general ā¦ a mattress is always a support system with a comfort layer on top (often with transition layers in between to make the change in firmness between the softer upper layers and the firmer lower layers more gradual) and then covered with a quilting/ticking. Each of these has an effect on the qualities and properties of a mattress and how suitable it may be.
There are many mattresses and layering combinations that would provide similar pressure relief, posture, and preferences to this mattress although there may be many different āpathwaysā in terms of choices of materials and layering that would provide this. The MySide is unbelievably expensive here as well IMO and Kingsdown who makes it tends to not provide the specifics of the materials that would justify the price and make meaningful comparisons with other mattresses possible (probably because there are no materials that would justify these prices and if they provided this information it would be too obvious that the prices couldnāt be justified). This is a common issue with most larger national brands who like to sell mattresses based on marketing āstoriesā rather than on the quality of their materials.
Rather than trying to āmatchā this mattress though ā¦ the goal is to think in terms of pressure relief, posture, and preferences regardless of material.
I spent some time looking for some of the better choices in and near Brisbane and in the next post when Iāve had the chance to take a look at them a bit Iāll make some comments about the two you mentioned as well as some of the other that are reasonably close by. It appears that you have some good choices.
Phoenix