Well, I did them yesterday. Just figured I'd rip it apart and figgie it out. Sure enough, there was a "gotcha". As you do with disc brakes, you have to get the piston retracted back so you're able to slip the caliper back on. Well, I got a clamp, started turning, and the piston would not budge a smidge. I'm thinking it's seized up in there, but it looked pristine. Then I thought maybe the fluid wasn't getting to the caliper, so I tore all the lines off, and pulled the caliper. It was full of fluid, so just as I was about to order a new caliper, I had an epiphany (which is rare for me). The end of the piston was slotted, like in a cross pattern. I got a wide wood chisel, stuck it in a slot, and sure enough, the piston started to turn back in. The dang thing was threaded. I NEVER came across one that was threaded, that was a first.
The little rotor on the ATV is centered above both rear axles, so there is only one brake that operates both wheels, and only one set of pads. BUT, one set of pads, which are only about a couple inches long and wide, were $43. WOW ! They get ya comin' and goin' on those machines, cuz they know you can't go to NAPA and get them.