Hi brooklynite,
I called them and they use 1.2 lb polyfoam in the comfort layer (ILD 15) which is low density and I personally would avoid it.
We don’t have any members in the NYC area but Post #2 here includes some of the better options in the NYC area. I would tend to talk with the first 4 on the manufacturers list and the first two (one of which you’ve visited) on the retailers list.
If you call them first and let them know your budget and your weight, sleeping positions, “challenges” (pain issues) and preferences (it seems to be an innerspring with foam on top) … they will be able to give you a few recommendations that they believe would be worth trying, the reasons for their suggestions, alternative options, and prices so you can decide which are most worth visiting. With your back issues … I would pay particular attention to both your support layers (to keep you in alignment) and the quality of the materials in your comfort layers to avoid pressure issues. I would also suggest if your budget allows it to go with latex foam in the comfort layers because it is cooler than other foams and also much more durable. Memory foam is generally the hottest foam … followed by polyfoam … with latex the coolest of all. There are a few manufacturers on the list which don’t use any foam at all in their mattresses (using natural fibers and innersprings instead) which would be cooler yet but these more “old style” mattresses tend to be more expensive and are different from what most people are used to. I would also tend to go with ticking and quilting materials that are natural and/or breathable.
You have some good options near you and a few calls to explore your options followed by some personal testing with the help of some knowledgeable people should result in a good quality/value choice.
Phoenix