Pete
BANNED
I'd agree with you as far as consistency goes --> same locations, widths, etc.. which is much harder to do in a consistent fashion using multiple stones, but Jeff Fowler believes that when it comes to final seat sealing surface quality, that stones will be as good or better than carbide (depending on who is doing them).
With that said, seat machines like a Serdi sure speed up the whole valve job process in a big way.
If I was going to have a knee or hip replaced, I sure wouldn't want one that had been finish ground instead of machined.