I agree with your line of thought on the rot issue Arlyn. I have only lost two plants, but the blooms from 25 or so. They were medium to larger rhizomes with multiple increases; some with many increases. All of the babies have well defined roots and the major area was in my re-bloomer bed/micro-clim area.
I have had a chance to go over other areas and I have much less or no rot going on. I had rot in brand new beds or in the micr-clim/re-bloomer beds for the most part only. The two year bed (ie second bloom year coming up) will be spectacular based on the increases and the size there in.