Curious: Did you consider the Purple? I tend to get pretty hot at night (no AC) and that one seems to boast the best marketing jargon with regards to cooling. Can you speak to the breathability of the others you've tried?
Obviously check reviews and everything, but I've found that as helpful as the reviews are, nothing is even close to your experience with the mattress and how you sleep on it. So if there is some brand of a bed that interests you, you should just get it and then return it if you don't like it.
One note though: The return process is easier if you buy it directly from the company and not through Amazon.
I'm still not entirely sure what differentiates its material -- which it calls Air Foam -- from memory foam, because it feels very similar to other memory-foam mattresses. And the website doesn't do a very good job of explaining precisely how the materials differ.
It hasn't seemed any warmer than our old spring mattress, though, so I guess its "100% temperature neutral" claim holds up.
But as OP's post points out, the mattress review sites are very little help. It seems like they're all affiliate-link driven. I spent a good long while trying to find a review site that seemed trustworthy and that didn't make its money through referral links, and I finally gave up and decided I'd just have to try my best to evaluate each company's claims on my own.
Speaking of referral codes, it seems as if for Nolah, there's an almost constant $100 off code that is advertised on the site itself. Nolah also runs a customer referral program, where if you use my referral code, you get $75 off and I get $100 for the referral. Which is crazy. Why would you ever choose the $75 discount instead of the $100 discount? It's almost like you have to be willing to screw your friends over to participate.
That said, if anybody wants to PM me and obtain my $75 referral code, I will be donating any proceeds to the Trappist Caskets Child Fund, which provides caskets free of charge to families who have to bury a child: https://trappistcaskets.com/child-fund/
The telling aspect of their marketing/FAQ is they actually tell you to expect this: they claim that years of sleeping on poor mattresses has conditioned your body to the wrong position and so it will be painful for 1-2 weeks while it corrects to their one true mattress. This seems like a load of bs. I've slept on hundreds of mattresses across the spectrum, from quarter inch closed-cell foam pads on top of rocks/roots to various hotel luxury mattresses and everything in between - and never experienced this level of painful need to "get used to a good mattress".
https://33ao321eg6ir3l6jee4fcxzi-wpengine.netdna-ssl.com/wp-...
Bottom line takeaway, and many might disagree, you can get a perfectly sleepable great mattress for less than $500 and anything more than that is straight up marketing cost or at the very least severe diminishing returns on your value.
The only issue (and it's a very slight one at that) is the weight of this pillow. I think the shipment said it was just shy of 10lbs. The best way I can think of to describe this pillow is that it's like a sack full of ass fat.