The black MMr has the inlanes wired backwards, and the left switch is flakey as well. Mechanical issues, nothing about the new platform. Agree on the flat-ness, they play a bit slow. I hope they make one of the games steep and turn up the flipper strength. The power here seems fine, all the games are playing great.
Couple other minor bugs on all three games: the duke of bourbon insert flashes without any incandescent emulation, and the DMD animations occasionally 'tear' .. usually ones ones involving flashes or lots of animation. The cabs and playfield do look nice, colors are nice and vibrant. Castle boom and such seems fine.