Hi ttran,
There are too many unknowns, variables, and personal preferences involved for anyone (including me) to recommend a specific mattress for someone else based on specs or “theory at a distance” (see mattress firmness/comfort levels in post #2 here). I can certainly help with “how to choose”, how to lower the risks of an online purchase, and how to avoid the worst choices, but the specifics of “what to choose” is up to you and your own “informed best judgement”.
The Amazon listing doesn’t provide all the specs of the mattress you would need to make an informed buying decision (see this article) so I would certainly want to know this before making any purchase. There is also more in posts #3 and #4 here and the posts it links to about Dynasty that I would read before buying any of their mattresses.
There are three key questions you will need to answer before choosing a mattress that are the most important parts of the “value” of a mattress purchase (see post #13 here).
The first of these is “how well am I likely to sleep on a mattress?”. To answer this you either need to carefully and objectively test a mattress in person or if that’s not possible then the most effective approach is to talk with a knowledgeable and experienced online retailer or manufacturer that has your best interests at heart and is more interested in helping you make the best possible choice than just “selling you anything they can” so you can decide on the suitability of any mattress you are considering in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). No matter what the cost or quality of a mattress … if it’s not suitable for you to sleep on then it would have little value to you.
The second of these is “how long am I likely to sleep well on a mattress before it loses the comfort and support that was the reason that I bought it in the first place?”. All mattresses will soften and break down over time until you cross the thresholds between sleeping well on a mattress (assuming you did when it was new) to sleeping “just OK” to “tolerating it” to deciding that you need to replace it. No matter how well you sleep on a mattress when it is new … if the materials are low quality or there is a weak link in the mattress (see the guidelines here) then foam softening and the breakdown of materials will happen much more rapidly (sometimes in months). There is also little value to a mattress where you don’t sleep well on it for long enough to justify the price you paid … even if you did when it was new.
Finally there are all the other objective, subjective, and intangible parts of your personal value equation that are important to you. This is where you can assess the cost and risk of a purchase and the options you have after a purchase (and the costs involved) if your choice doesn’t turn out as well as you hoped along with all the other factors that can help you make meaningful comparisons between your final choices.
One of the most important parts of the process of making an online choice is your more detailed conversations with each manufacturer or retailer you are considering and without this you are really just “rolling the dice” or “throwing a dart at pictures on a wall with your eyes closed”.
Phoenix