The point about specialists is a good one, but i generally feel the need to rate a batsman who has proved his ability in a variety of conditions a "greater" batsman than a specialist ike Sehwag, Mahela, etc, even though in certain conditions, the specialist may be a bigger asset.
As for the point about short tours, that's very true. Sanga couldve done better in certain countries if he had been given more opportunities but you have to go with what you get. He's played two match series in England and South africa each, which is pretty standard, and has done very little of note.
I'm just afraid that people are assuming just because i prefer KP to Sanga, it means i think Sanga is crap. Far from it... he's an ATG, but today, i picked KP... another day it might be Sanga. Both are great batsmen with their own inherent limitations