Is it true that cgminer is best for GPU mining and Ufasoft is best for CPU mining?
Yes and yes, that is true on both counts.
Sam
I suppose you haven't tried my fork of cpuminer.
It should be significantly faster than Ufasoft on most (if not all) processors, and is the only miner to provide optimizations for AVX-enabled systems.
A brief introduction to the fork is available
here.