90 day return policy so I am willing to take a chance. Also, the viscous mattresses from Sams are all priced under $650 from Kings.

Has anyone ordered any of these? 

Nope, but I do have a caveat: You might want to measure your mattress after the requisite 72 hour period for full expansion. My memory foam mattress from Wal-Mart (Aerus Natural 10") is two inches short length-wise, and a half an inch short in width. I don't mind that it's not quite as wide as specified, but I feel cheated on the length. At 5'6", my toes should not be dangling over the foot of a full-size mattress!

5 nights on this and it is firm, very firm. The bottom 9 inches is a firm PU foam, but the top 3 inches is I believe a 5lb memory (visco). I like the firmness at first, but it becomes uncomfortable after laying on. I think because I am not getting enough lumbar support.

I ruptured my L3L4 disc last August and have been on the mend. However, since using the mattress, I right leg is getting pressure on the nerve which I have not had for months while sitting 

Any suggestions? Do I look  for a topper, will it help? Or just bring it back.

It should soften up after you've slept on it for a month or so. If you want to break it in quickly, throw it on the floor (unless you have a sturdy bed frame) and walk on it.

Mattressmeister wrote:
i would say send it back. it is true retailers tell you to give a new matt a month or so to 'break in' but this is more to do with letting your body get used to the new feel and loose its 'memory' of your last one.

you say you have had some pretty serious back problems in the past and it is obvious the matt you have is to firm, make sure any matts you try are soft enough to let your hips and sholders into it with out sagging and lie on it for as long as you like in whatever positions you normally sleep in, just tell the sales guys to go make himself a cup of coffee as your going to be there for a while.

The fact is, you bought a mattress that you have know idea what it is made of.  It's cheap.  Theres a good chance it is a chinese import which don't carry the same regulations as U.S.  manufacturers.  In a few months you might be sleeping in a hole.  Then you'll be back on this forum preaching how bad memory foam is.  Take that thing back and spend your money on a cheap firm mattress and put toppers on it as needed until you can afford a good quality set.  Thats just my opinion.  You get what you pay for.