Hey Phoenix,
Sorry it took me so long to get back to you; after I made a realization that I would have to start all over searching for a new mattress I burned out and then the holidays came but I'm back up now
I want to thank you again for all the hard work you put into the research for the Nashville area and I put it to good use. I narrowed down the retailers/brands based on your list and went to a few places and I think I have what I'm looking for; just would like your take on it from a technical standpoint to say yay or nay (I know it's up to me for the 'feel' of it but you are the details guru so...) I'll spare the story and just give you the specs:
Dutch Craft Dr. J's Spinal Health Collection - Embrace model (Queen)
As best I could tell, this is a "Private Label" Version of
Dutch Craft's Paradise Gel
based on composition and similar specs. This mattress was created in cooperation with a local Chiropractor in Lebanon, TN and as a private label sold only to that store, I could not get a lot of the gritty details of the foams beyond some density and other info but since you trust this company and I've heard a lot of good things about them, I wasn't too perturbed by this. From the websites of the maker and retailer, and brochures and retail staff I've gleaned all the info I could at the time.
Comfort Layers:
2" of "High Density" Chiro Cool Gel (Unknown Density/ILD) (Cooling gel mixed with visco-elastic foam; process used unknown)
2" of 5 lbs. Soy-Based Memory Foam (Unknown ILD)
Support Layer:
7" Soy-Based
Preserve High Density HR Foam Core
(I read on the retailer's site that the core has a 2.3 lbs. density but couldn't confirm this with Dutch Craft / Unknown ILD)
Foundation:
Poplar Hardwood (I thought I remember reading an article on this site or somewhere else, or maybe you told me, that the welded semi-rigid wire foundations were better than the wood slatted ones for memory foam but in any case, this is the one it's coming with; I saw a picture of it on the Dutch Craft site and it's an understatement to say they overbuild them; it looks like a tank

)
Warranty:
20 year non-prorated
I am slightly concerned about the soy based foams (as I haven't even heard of them before) and if they would breakdown faster or have other issues that petrochemical-based poly foam types don't have but I guess I can be a pioneer

(I suppose a good side effect of using soy foams is less offgassing/healthier sleeping enviornment). But other than that, the bed felt very nice; proper comfort/pressure relief and support/alignment. Do you happen to know or could find out anything about these soy foams used especially the Preserve HR core? How it stacks up against CertiPUR-US or other high end foams?
Another thing I was mildly concerned with was the 4" comfort layer (Thicker than the bed I'm having issues with now) but the foams are pretty firm and even when laying on my stomach, pulling my lower legs up (which usually forces your lumbar into the swayback position) my stomach and back stayed flat. And on my side it sank enough to not hurt my shoulder but didn't put me out of alignment.
I tested a lot of the Jamison models as you suggested since those two companies were the most recommended and I found some I liked, but even the highest end GelComfort/JGels (Oceania and Pacifica) used lower density, convoluted comfort layer foams (which is a shame since everyone talks up the 7" High Resiliency Marriott Core) and were charging close to $2000 (And latex is a little too springy for my tastes but I tried those models as well) so I decided to try out the Dutch Craft and here I am.
Anywho, sorry for the long post just wanted you to have as much info as possible to evaluate. Let me know what you think.
Thanks.