Hi zen4life,
While the PureRest is certainly less … it has no latex in it and with just the cotton and wool would be very firm … and would get firmer as the cotton and wool compressed.
Even their innerspring/latex hybrid … while it is two sided (which adds to value) … only has 2" of Dunlop latex on each side which would also be very firm.
One of our members also sells a similar firm one sided innerspring with wool and cotton over the springs and a 2" Dunlop comfort layer which is here.
I would never buy latex … or pretty much anything else either … from Foambymail (FBM). More about that in post #2 here (and the posts it links to). For me … getting what I want and expect is too important in a mattress to play around with “luck of the draw” materials. They are one of those cases where “cheap” can be very expensive. As you mentioned … they would be way too big a risk for me to consider as a reasonable option.
I would personally either work with a local manufacturer like you are or talk with Bay Bed to see what their equivalent modular mattress would be.
Phoenix