Hi Jnotari,
Welcome to TMU. I will be very brief and get back later. I disagree with your assessment of having to settle for a national brand. I don’t believe that is true, even in the situation you describe.
Testing a mattress for 10 min, 20 min, is helpful, but it still is no indication of long term comfort and durability. The reason it is difficult to evaluate many of the national brands is because they don’t really provide the information necessary about the materials to predict long term durability, short term comfort or the ability to compare mattresses within their own lines, sister brands or other competitors.
HMMM! I wonder why?
I have mentioned this many times. I did the national brand search and trial. Narrowed down to a few based on my personal preferences, pressure relief and perceived posture and spinal alignment. Then I compared my final 3 or 4 choices which varied from 3k to $14k, give or take. I looked at each, layer by layer, side by side on the computer screen, density, weight, materials, construction, coil gauge etc. All this was prior to becoming a member of TMU, and perhaps might have evaluated with even more intensity, then I did prior to being a member.
Anyway, the mattress I chose was a BinB, never tested it, slept on it, heard of it, except for when I searched the internet (after much frustration, similar to yours) for the “firmest mattress on the market.” The Brooklyn Bedding Plank Luxe kept showing up, time after time. Saatva was in there too, big fig, winkbed and the titan. I studied as many independent reviews, what I consider off site (non affiliate, not on the manufacturers or sellers web-site. I watched every affiliate website review of the mattress, for the purpose of finding out what the mattress was constructed with. They seem to get more information than the websites of the respective mattresses provide. I took their advice with a grain of salt, but utilized their reporting of the materials and construction.
Now it may be easy for a manufacturer to say their mattress is the “firmest.” If they provide actual specs, you at least have a chance of testing their claim on paper. Thicker gauge coils, HD Foam, 1.8lbs or more, higher ILD of foams vs. lower ILDs, natural fibers the firm up when compressed, and so on. That is exactly what I did.
I reviewed any seller’s 3 R’s, return, refund and restocking fee policies. What was my exposure, what is the trial period, what happens if I dont like the mattress, and what is the complete process of handling the 3 R’s?
I will say since joining TMU, all of the Trusted Members spell those issues out with clarity and layman’s understanding. Some policies are better than others, certainly, but they are transparent about them. Most ship nationwide and offer trial periods. Some have body profile mattress testing. Some more detailed than others, but most seem to nail it on the first try, considerably more often than folks just wondering into the box or department store and being “sold” by a salesperson. I am not suggesting there are not good salespeople out there (so lets not go there), good experienced ones are out there, I crossed paths with several. That is why it is important to do some research prior to walking into any mattress store. You need to know if someone is being sincere and accurate or are they just “selling” it.
I would start with identifying your body profile, age, weight, and bmi. Personal preferences, past history and what you loved about your previous mattress. Even if the mattress only lasted 3 years. You objective would then be to match that model of mattress with one that can be built or bought with similar characteristics, but with a level of quality that will provide for long term usage. When the specific model of past mattress is available, provide it. Size of mattress. I cant tell you how many times people post here and other sites, “looking for comfortable mattress for users with different preferences.” Well, great, some companies only make dual comfort in a king sized mattress, some in both queen and king. How can anyone point a prospective mattress purchaser, if they don’t know what size mattress they are looking for?
I have looked at many of our Trusted Members websites, spoke with a lot of them via posting, text or email. They all were happy to respond and offer their perspective on things, even when we had differences of thought on a subject. But that is how you learn as they see folks hundreds of times per year, where the prospective mattress purchaser, may only see them once over a period of many years. I have patients who do this to me all the time. I have to remind them, I see “you” thousands of time a year, you see me once a year. I can remember every detail of your visit. LOL 
I guarantee you that you dont have to settle. Just put your info out there and one of our trusted members can point you in the right direction!
Probably not the answer you were looking for, but just my way of providing helpful tips on entertaining the process.