So, is FBM's 5.5 lb Memory foam pretty decent nowadays?:  http://www.foambymail.com/SRFTopperFull.html  I'm thinking about trying some.  If I had the money, I'd buy 8 lb memo-foam somewhere.  I'm not much concerned about it sleeping "hot".  Most important, I like it dense.

I might consider an IsoForm: http://www.isoform.com/2inchisoformmemoryfoammattresspad-p-42.html .

 

Unfortunately, my budget can't exceed FBM's charge for their heavy 2" full-size topper.

 

I decided to go with 2" of Isoform.  It's not as dense-feeling as I would have hoped.  I calculated it's density to be 5.33.

Though it's not as nearly as gassy as the ~4lb gel topper from Costco that I returned.