Been on R4 for awhile now. No offense to Juicy, but R4 is what we call in the Linux/software world a "regression." I'm on my phone, so correct me if I'm wrong, but it's most likely due to the switch to the USC 6.5 CDMA base. That's understandable.
If you guys want to revert to R3, I have it up on my mirror (that Juicy still won't use, his loss) :
http://ppc.mutiny32.com/JuicyROM/