Patti, yes, I did find it heavy to move around. I bought an 8ft long table just to deal with it. The table isn't very wide (about 30in, I think), but it meant that I could spread all the layers out without them falling off the ends. I used small spring clamps to hold the backing onto the table at one end, put the other layers on and clamped them too, before I pinned.
Then once that first 30in was pinned, everything got unclamped, pulled towards me, reclamped and I pinned the next section. No way was I going to crawl on a floor ever again. (The previous quilt nearly finished me off, so that table was an investment)
I agree about all the seam allowances, that does make the quilt heavier than you would think. As for making two of the back to back Debbie, you would have to really like weight on your bed - plus, have you contemplated how to join them together? Even if you are doing the QAYG thing that I did - would you do that for both 'tops', what would you do to hold the two layers together? I think you would be extremely lucky if you managed to line up those blocks and still get it to lay nicely if you wanted to stitch in the ditch round each block.
I suppose your best bet would be to get a long armer to quilt an all over design on it (them) - is that what you had in mind?