I think Maldonado is quicker than Sato, more feisty (good and bad) and better under pressure. I'd say Maldonado is closer to somewhere between Ralf Schumacher and Massa. I think he could win multiple races in a top car but inconsistent and I expect he'd always find a better teammate alongside him in that situation. I don't see a WDC in him tbh.
Maybe Maldonado is quicker than Sato though I remember Sato outqualifying Button quite a few times, while Maldonado was outQ-d by Bottas. So I don't find it clearcut and it is a difficult call to compare drivers from what can be already called different eras/generations.
Multiple race wins in a top car? Depends, how good this "top car" is. Webber couldn't win even in RB9. Maldonado is considered fast, but I don't think he is so fast he can outrace top driver team-mates on a semiregular basis (even disregarding inconsistency). He reminds me more of an inconsistent No2 driver. Let's look at Webber in 2013. There were a few races, where he competed against Vettel, like Malaysia. Most of the time he was lagging behind, sometimes by big margin. I expect no better from Maldonado, plus you can add he may make more bonehead moves.
I suspect Maldonado's highly-rated "speed" will be found out against top drivers. Not that he is slow, but he isn't quite at that level on a regular basis.