Our experience has been good with them. We have been keeping clubby heifers as replacements since 07. Among the sires of these females have been All About You, Eye Candy, Gigolo Joe, Boarwalk, Who Made Who, and Monopoly. From those cows we have kept some of those females that were sired by I-80...
From our experience, I-80 is the way to go. At first we only used I-80 on THC cows, but now we would use him on THF cows as well.
There's nothing wrong with Daddy's Money, but for us the I-80 calves have much more power to them.
As far as calving ease, we found our Daddy's Money were smaller...
We've had 30 or more Eye Candy calves and we have only had 1 with a bad attitude, in that case we blamed the cow. We have replacement females from him that have never been a problem.
In our experience, breeding purebred angus cows back to club calf bulls works out very well. We use proven bulls about 90% of the time.
The other factor is that you need to have is good cows, doesn't matter what breed they are, they just need to be good.