Hi Barnaby,
You’ve done some great testing and I can see that you have a good sense of the different types of materials and the “feel” of each.
This can be a good idea. The two types of what could be called “vertical” zoning are a side to side split where each side is layered differently or a “regular” layering where the layers get softer as you go up (which is a typical construction and isn’t normally considered to be “zoning”) where different layers have a different function for each person. Both of these can work well.
I can certainly understand this and the mix of latex and memory foam in various combinations has a nice “feel” that many people like. Finding this type of layering is a little less common though … at least in a mattress that doesn’t also use some lower quality materials in the mix.
The PLB at this stage is by far the most common brand that uses more “simple” forms of this type of latex combinations outside of local manufacturers. While Latex International makes slow recovery latex (it used to be called NuForm … and is now called Talalay GL slow response latex) … it hasn’t yet appeared in many mattresses that are widely available. The fast response latex with phase change materials used to be called Celsion and is now Talalay GL fast response. Both of these have phase change materials in the latex to help with temperature control. You will have some difficulty finding it outside of PLB (although it is available as a topper including from one of our members). Good quality memory foam (5 lbs or higher) can be quite durable (more so if it is under another layer) so I wouldn’t necessarily give up on it. In many cases … 8 lb memory foam can also be quite soft (often softer than 5 lb memory foam). Your best odds of finding the slow response latex hybrids would be the Pure Latex Bliss website retail outlet finder. There are quite a few outlets that carry PLB near you but many may not carry the hybrid line.
This is a very popular type of ticking for use with premium foams (memory foam and latex) because it allows the properties of the foam to come through more. Wool quilting is also popular because it can add to breathability over any type of foam (including latex) but will modify the feel of the foam under it so varying degrees (depending on the amount and compression of the wool.). For those who like wool on top of other materials … it can be added separately as a protector, mattress pad (a little thicker) or as a topper (thicker yet).
The specs on the PLB models have recently changed and are not quite the same as are listed on this site (and other places as well). They now use Talalay GL (what PLB calls activefusion) fast response in the top layer. The lower 1" layer is also now gone and has been added to the second layer down.
This means that the Beautiful now has 3" of Talalay GL fast response over 3" of Talalay “natural (which is actually blended talalay) over a 6” core of firmer Talalay (36 ILD).
The Nature now has 2" of Talalay GL fast response over 2" of natural Talalay (blended) over a 6" core (also 36 ILD). I believe the ILD of the layers is the same but the layer thickness of one of the top layers i not an inch thicker.
At this point both the old and new are still available during the lineup “transition”.
The Beautiful has 6" of “soft” latex on top (19 ILD and 24 ILD) which would have some risk for alignment for someone who was heavier so whi8le there’s no doubt that the pressure relief would be good … I would make sure and confirm that your heavier parts weren’t sinking in too far. This would be an unusually soft top 6" for someone of your weight (although I know it feels great :))
TempurPedic:
Given your “stats” if I was looking at the Tempurpedic line I would avoid the Cloud series because of the 4 lb memory foam and would likely be looking at the HD series, particularly the Allura and the GrandBed (although the GrandBed with 7.2" has more memory foam in it than I would be comfortable with in most cases). Their 7 lb HD memory foam is actually softer than the regular 5.3 lb memory foam but also more “supportive” (relative to their other memory foams) and more conforming. Their ES 4 lb is the softest followed by their HD 7 lb and their 5.3 lb is the firmest. Did you happen to test either of these? The contour signature is the softest of the Contour line and may also be worth testing.
SleepHarmony Bliss:
These are made by Glideaway and like a few other mid size wholesale manufacturers can actually be surprisingly good value. I know several smaller mattress manufacturers that carry these instead of making their own memory foam mattresses (because of the expense of prototyping and testing memory foam mattresses) and think very highly of them. They use CertiPur certified foam. In this case however … the Bliss has 6" of 4 lb memory foam which would not be a good match at all for your weight.
If you are considering a memory foam mattress … I would talk with the two manufacturers on the list in post #21 here which specialize in high quality and value memory foam mattresses (including “breathable” higher density memory foams). Both of them can also make custom adjustments (if necessary) based on your feedback on the Tempurpedics.
Outside of possibly testing slow recovery latex … I think that you probably have enough good testing experience that now the next and most difficult part is to narrow down the combination of materials that you would prefer. Your choices are between inner springs, polyfoam, or latex in the support layers and memory foam or latex (or slow response latex) in the comfort layers. Once you’ve decided which is your preference in the bottom and top layers …then the elimination process can start to get more focused and easier.
You have a couple of very good choices in terms of quality and value locally and more options yet with an online purchase. After talking with them … one by one you should get closer to a final choice … as difficult as that may be. You are at a point where all your realistic choices are good ones. Now the hardest part may be deciding on what to exclude till you get to “the one” 
Phoenix