Hi rcseisland,
Welcome back!
FoamMattressDiscounts is Lasting Impressions Foam (along with a few other online names) and I’ve discussed them previously here in post #2, which is worth a quick read. I would recommend extreme caution and consider them as “buyer beware” for the reasons put forth in that post.
Yes, this is also listed in their FAQ section where they state that memory foam being open cell is more important than density, which isn’t accurate. Their statement on amazon of being FULL 5 lb density is derived by adding up the density of the memory foam (3.3 lb) and the density of the polyfoam base (1.7 lb) to create the 5 lb number, which IMO is meaningless and done to create the perception of the memory foam layer being higher quality than it really is. I advise people to avoid businesses that market in such a manner.
As you’ve previously taken the time to educate yourself B) about foams and mattresses, you were probably able to “sniff out” some of these inconsistencies even before making your phone call to them. Trust your instincts.
The Addable certainly would be a good choice for an affordable good quality/value mattress (they are members here of the site, which means that I think highly of them). Post #4 here and the posts it links to also include many of the better lower budget online options I’m aware of as well.
I’ve never been too much of a stickler for where the posts are placed, as long as they are relatively on topic and the replies are kept in the same thread. No worries!
I’ll be interested if you find anything else or make a decision, and of course any questions that you may have.
Phoenix