How old and big are the trees Bill?
For me, Kieffer can have some FB, but it generally affects only new growth and not all limbs. As a tree matures, it will still get some infections but not enough to be a serious problem. The larger the tree grows, the less the FB seems to matter,
It's also possible that you may not have real Kieffers. Mix ups in the nursery business happen all the time, and Kieffer has been around for so long, there are probably lots of strains out there that people call Kieffer that are something else.
Even in modern times things like this happen. There was a mix-up once with one of the best apples to ever come out of the PRI breeding program. People thought they were buying the PRI selection but they were getting something else that was inferior. The inferior tree was a scab immune apple, but it lacked the other many great attributes of the true selection. What a bummer - but bummers happen.
I have no trouble with Kieffer here. It is an outstanding producer almost every year, unless a late freeze gets it. But if that happens, it will affect many other fruit trees besides just Kieffer. Yes, I have seen some minor FB on Kieffer, but never a deal breaker for me.