For sweat issues: you can consider buying or making your own "coverband". The ones at the parks are a swimsuit-type material, like what a bikini is made out of. It keeps things much cooler than just wearing the band on its own, and it dries quickly. And
here is a tutorial for making your own.
Positioning: we started wearing them with the mickey head to the outside-side of our wrists. Then we would just choose the pole on the side we wear them on (like finding a gas pump, you usually go to the correct side for your car). Put the arm straight up, move the arm slightly to the side to make easy contact with the pole's mickey head. SO much easier than twisting the wrist.
As for paying for things, the readers are ALMOST made as though they expected us to put the mickey heads on the bottom of our wrist. Drape the hand over the reader; mickey head under the wrist connecting with the reader's mickey head, then for my hands it's *almost* perfectly positioned to key in the PIN without moving the hand much. (of course, this is a wonderful method of disease transmission; almost as good as the "honey wall" in the Pooh queue, which goes along with my amusing-to-me theory that Disney is trying to create an epidemic for some reason...everything they are doing just seems to involve touching!)
Those are my thoughts on the MB.

I totally thought it would physically irritate me, but it didn't cause a single reaction. Bothered me in other ways, but I didn't break out or itch or anything.