Hi megan,
It sounds like you are doing some good testing for PPP.
I would keep in mind that much of this (including your “memory” of the Stearns & Foster) would be quite subjective because our subjective memories are not particularly accurate. It’s also not unusual for people to “feel like” some parts are sinking in too far on a latex mattress even if they are in good alignment because it responds differently from other types of materials that they may be used to and because of the way latex contours to the shape of the sleeping profile but remains “supportive”. This is one of the reasons that it’s important to spend at least 15 minutes fully relaxed in your normal sleeping positions on any mattress you are seriously considering so that you can “approximate” and predict your sleeping experience as closely as possible.
Having said that … if you felt any tension that borders on discomfort or pain or couldn’t seem to completely relax and “let go” on a mattress when you were testing then I would consider a more supportive mattress with either thinner comfort layers or firmer support layers (such as the Nature). Thinner or firmer comfort layers are also less “risky” for stomach sleepers.
This is very much a matter of personal preference. I’m also a Talalay guy (especially in comfort layers) but my daughter completely disagrees with me and much prefers sleeping on Dunlop.
Post #32 here includes some retailers that ship the PLB mattresses across the country that may be worth talking to so you can make some “value comparisons” with a local PLB purchase. I also think that a visit to Maiden Maine would be a good idea as they also have some good quality/value latex mattresses.
I’m looking forward to finding out what you end up choosing :).
Phoenix