Hi mb321,
Thanks for the update on your research.
Most of the mattresses that Denver mattress makes use good quality materials and have good value and they are very transparent about their specs but I would avoid the mattresses they don’t make themselves which includes the major brands they also carry and the Green Choice mattresses that they import from China as well (see post #7 here).
I’m looking forward to “part 2” of your mattress search … and we’ll still be here to help if you need it.
Phoenix