I agree with Chaos here.
I've got caught up in a couple of fics that never did finish, and so now am reluctant to read long fics posted in parts on the mbs.
But I'm guilty of the sin of posting and not finishing too - a couple of years ago I posted the start of a fic which I had outlined - still have the stuff - but RL and who knows what else, etc - anyway I still feel wrong about not having finished it. It's like you made a promise you didn't keep.
c.