Re: PF + Wool = Rash???
My Babe has been in cloth her entire life (almost 10 mo now) and she has never had rash. You seem to do the same as I do with regards to changing her frequently. The only time her bum seems to get irritated is when she comes in contact with poo. Change immediately with every pooed diaper!
Give diaper free time every day!
If your babe is on solids you could also try to research foods that could be causing the rash as well.
If your babe still has rashes with the new detergent try another -- I use Charlie's Soap and it does a BEAUTIFUL job on my prefolds.
Allergy to wool may be a possibility.