I think Pietersen's ceiling as a batsman in an awful lot higher than Smith's.
The proof of this is in both having similar records and the consensus being that Smith has done very nicely, ta v much & Pietersen carrying the faint whiff of a forever unfulfilled potential. He'll probably retire (or have his test career ended by pissing off the ECB/his teammates once too often) as the highest English (yeah, yeah...) run scorer and century maker, but it still seems too scant a return for a man of his abilities.
It's a matter of record that I'm not Master Smith's biggest fan, when he first emerged he was, frankly, a fat blow-hard who told tales out of school but there's no doubt in my mind that he has matured as man. Experience has given him a sense of perspective. Still fat tho, obvz.
KP, meanwhile, seems to be caught in a permanent adolescent ego trip and, if one judges him on his actions, genuinely seems to lack any real sense of the consequences his actions have on other people.