I've been using Masters for about 500 miles or so. I started with 23's which were exactly 23mm on my Velocity A23 rims (23mm outer rim width, 18mm inner). Every other 23mm tire I've used was closer to 25mm on those rims.

But the ride was fine and they look great. I tore a sidewall on the rear after about 100 miles, so I replaced it with a 25 mm Master (which is exactly 25mm, fwiw). So I have 23 in front and 25 in back.

For mounting - they were tough, but not exceptionally more tough than my Michelin Pro 4 tires. I use Veloplugs on my rims and am really careful to pinch the beads into the center of the rim, and it works OK.