Hey Snoozehound,
Welcome to the Mattress Forum! :).
Thanks for the post. Although we are primarily focused on the North American market, we do try to help any AUS consumers that come to the forum. I am not sure how much of the site you have read so I may end up going over links you have already read.
While I can certainly help with “how” to choose … It’s not possible to make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or combinations of materials or components because the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort”, firmness, or PPP (Posture and alignment, Pressure relief, and your own Personal preferences) or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress), sleeping positions, health conditions, or “theory at a distance” that can possibly be more reliable than your own careful testing (hopefully using the testing guidelines in step 4 of the mattress tutorial) or your own personal sleeping experience.
A forum search on Naturatex - at this link.
This post #2 herealso has many links regarding AUS companies, and additionally, this post has good content for general mattress purchasing guidelines.
Just a couple of comments about some of the brands mentioned.
Mattress Builders - I don’t see any certifications for organic latex, and Latexco, a very high quality leading latex manufacturer does not make a certified organic latex. They should just say 100% natural latex…addtionally I wish they used progressive layering- progressive layering.
Don’t assume the Zenna is the same as the mattress builers, as there are so many factors…fabric, manufacturing process - finishing, cover style, quilt contruction to name a few that can effect feel. Also putting 6 + 2 together will feel different than one solid piece.
The fernearth is similar to the Zenhaven latex in the USA - flippable, and they don’t seem to have a problem with the softer layer on the bottom. Plus the Sri Lankans make and sell pretty firm latex, so not sure how “soft” that bottom layer will be anyways.
It is hard to diagnose the NaturalSleep issues, as the site and differences between all the mattresses is not well explained. I will leave that to you researching more on this site and asking more questions.
I hope this helps a little, we don’t really have enought time to do a deep dive into the USA brands, so we can’t really committ to researching AUS too much. Good luck, and please ask other questions you may have.
Sensei