Difference between Malkin and Parise is much bigger than the difference between the other 2 combined.
Fleury posted a 0.913 save%, Backstrom had him beat at 0.919% however Fleury played 20 more games, that's a significant difference. His playoffs were awful but that was only a 6 game sample, so if you wanna drop Fleury that far because of it, that's your opinion.
As for Suter and Letang, Suter has the edge but it's definitely close, at least until we see how Suter performs by himself.
Malkin has a significant edge over Parise, and since you're seemingly using recent play as a big factor, the difference between Fleury's .913 save% and Backstroms .919 isn't nearly as big as Malkin's 40 more points in 7 less games over Parise.
Your citing one season as an example. Backstrom has put up better numbers consistently even when playing 60ish games.
Backstrom doesn't need to play much more than 60 games because Harding is practically a starter himself. We feel plenty comfortable giving Harding the start whenever we need to. That and I swear Backstrom has a stretch of a couple weeks where he's either injured his groin or his back every single season.
I think Fleury on his best nights would be better than Backstrom on his best nights. On the other hand, I find Backstrom to be more consistent. I'd have to go with the consistency on this one. Backstrom for me, but it's pretty close.