He definitely had it easier coming on to bowl after Donald, Pollock, Ntini, Steyn, Morkel, Philander (I realize not all played together) had blown away the top order or had softened them up. This may or may not reflect in the numbers (in the case of Zaheer vs Kallis, it definitely does) but it is certainly an argument worth pondering over. The workload he had was nowhere near as much as 'proper' front-line bowlers viz. Anderson, Zaheer et al; hence it would be unfair on both to compare them purely on averages (as Tendulkar+Zaheer seems to suggest). You could also split hairs and argue he was more likely to get to bowl in a relatively easy situation/used more in suitable conditions/taken off the attack when hammered etc.(luxuries that premier strike bowlers do not have, in short).
He compares favourably with the great all rounders and he is an ATG, no objections there. Gotta agree to disagree on the Lara/Ponting thing. To me they were definitely better batsman by a margin not negligible enough to make me consider the other added advantages they brought to the table. By a better margin I don't mean a Bradman vs Martin type margin, just a clear and definite margin. If I didn't have enough 5th bowling options or the front-line bowlers were utter crap, then I'd probably go Kallis.