Ok, let me ask you this Sean, when you proof your 4x5 negatives, maybe putting 4 in one sheet of 8x10 paper, dont they always seem sharper and with netter tonality than when you enlarge them? This is how I became hooked on contatc printinting, I always noticed my negs had a much better quality that those enlarged. Now I could acheive the same quality after much burning and dodging, but it always seemed to me that the contact prints appeared much easier to print. Once I moved to 8x10 and 12x20..I have never looked back. Next time you do some 4x5 try this, and you will see the difference.
Many people allege that there is differences in micro contrast etc, etc. I am not that technical or interested in the reason why, it just seems to me that contact prints have a quality that is hard to acheive when enlarging.