It has been a while since I've posted.  I am happy with the bed I have now.  Here is a summary of the entire saga:

Flobed:  I purchased a Flobed in early January.  I got the setup that was indicated to be firm. It was too soft for me. I did several core exchanges to get super firm cores but still too much of a sag for my back.  I returned it in April.

Stearns & Foster:  I bought a firm bed from Sears.  If you don't like the bed, you can return it within 30 days, no questions asked.  It definitely did not sag which was a big improvement but it was quite hard.  I woke up with backaches because it didn't provide any arch support to my back.  I had seen reviews of latex mattress toppers on this site and decided to order a 2" topper from foambymail.com.  They definitely seem to have the best prices.  They offered choices of a soft topper or a more firm one.  I decided to order the firmer one.  I've had it for about 2 weeks now and the bed is fantastic.  No more backaches or other pain, still have great support and no sags.  I may have been able to go with the softer topper as this one feels quite firm but I am very pleased and look forward to many years of comfortable sleep.

And now a couple more comments about Flobeds.  They were very pleasant to speak with.  They gave me no hassles when I asked to return the bed.  The only issues I had were related to getting reimbursed for core exchanges.  It takes up to 3 weeks to get your money back but they often exceeded the3 weeks and I had to remind them several times that they owed me money.  They returned the money for my original purchase but I had upgraded to 4 super firm cores during the test period.  On top of the other refund requests I made,  I had to request an additonal refund for $80 several times before I was reimbursed.