Whew - we’re finally done! Well, aside from the details and the tweaking. 
We managed to make it in to Black Sheep, Sleep Boutique and Halstead this weekend, due to some work flexibility on my part and some appointment flexibility for Sleep Boutique. To start, I have to say we got some pretty amazing service at nearly everywhere we went (Sears was the one exception, and I expected nothing less). Rory at the NE Sleep Country was actually far more knowledgeable and helpful than I often expect from a chain, and everyone at the smaller local stores really went above and beyond. Very grateful for how helpful everyone was.
Black Sheep was the first visit of the weekend. They do their all-latex mattresses in 3 thicknesses - 7", 9" and 12". The 7" was the closest to our budget, but we didn’t feel that it was thick enough to get the desired firmness combo to let my husband’s shoulders drop in far enough to keep his spine aligned. 9" was definitely better, so it went on the short list. It was still overbudget ($3200 before foundation), but at least closer than the highest end ones, and a better fit than the lower end ones.
Next to Halsted. Discovered to our delight that they also do the zoning (head/middle/foot) like we’d seen in our favourite bed. Tried out some permutations and got one that felt very good. Then he did the pressure mapping on that and found that it looked pretty perfect for me, and a touch too soft in the middle for my husband. Minor change for that and it looked better on the map, and felt better to my husband as well. Tried a couple of other swaps just for science, but none turned out as well. (I was happy to see our judgments aligning so well with the readings. Kinda reassuring.) And the price actually came out very close to the top of my budget. Slightly over, but within sight (about $2600 vs our top-end desired 2500, including foundation).
Given that we liked it the best of anything we’d tried so far, we were feeling pretty sold.
We still had an appointment at Sleep Boutique, though, so figured we wouldn’t be hasty. We checked out their options as well, and I think this would have been our pick if Halsted hadn’t worked out as well as they did. Their latex mattresses were customizable as well, and also seemed to be good quality, but the one thing they were lacking was the zones, which made a fair amount of difference for my husband’s comfort and some for mine. The price point was lower, though (about $2100 before foundation - can’t recall how much the foundation was), so if we hadn’t preferred zones it certainly would have made sense for us.
The other thing we have to factor in for cost is that Halsted does have a delivery fee, although given how everything but the top layer is in thirds we can just pick it up ourselves easily enough. We will have to take care of getting rid of the old mattress and box, though. We may try listing it on kijiji for free - it’s not comfortable for us anymore but it may work for a while for someone who can’t afford anything; alternately there’s a recycler in town called Re-Matt, and they’ll pick up for about $100 IIRC.
So yeah - we just need to iron out a couple of details with Halsted tomorrow but it sounds like we’re set. Now to wait the [strike]eternity[/strike] three weeks until we can get it! Hopefully this was helpful for anyone in the Calgary area - feel free to respond here or message me if you want any further info.