Form a non disc convert, they look very miniscule. Would that be normal for disc brakes? From a wise old b'stard point of view I think, that will take a lot of cleaning after a muddy ride !
I may be wrong but in mechanical disc brakes, only one pad is actuated so the calliper body needs to move ot ekse pad wear is uneven. With hydraullic both pads are pushed by the fliud pressure.
On mechanicals I've used one pad moves, the other is adjusted close to the disc, the disc flexes slightly against the static pad. The static pad us adjustable for wear.
Hayes sole ate hydro but work the sane, one actuating pad.
All other hydros I've used are dual actuating pistons.