I've got M770s which are very similar, on my fast commuting bike. They date from 2008 or 9, so post "Parallel Push" type. They're absolutely fine, work as well as any other XT brake I've had
M770 here and they work well, of course pretty much the same as the M580, just take your pick on the colour you prefer (I have and use both)
I think both these look better than the M780 though. A bit less in your face, a bit less modern.
Can't really fault them and lighter than Parallel-push M739's (also have and the M950's)
Got four lots in my toolbox and on the bike. Rust may have screwed them from living by the beach. Bike is going to be split now after a recent purchase so lots of goodies off it to be had.