Well, I'm making that full-frame jump.
I found a 5D (w/grip) for a nice price. If the camera is in half as good a condition as was described to me, it'll be outstanding. The woman I'm buying it from used it as a backup to a 1Ds MKIII, and she used mainly the 1Ds MKIII.
So, hopefully all goes well, and I'll be adding a full-frame to my gear list around noon tomorrow...