I have used this on various wheels for a few weeks now before leaving a review. On the R20 Evo, the Turn Plate is perfect. On a P310, I use the 5mm spacer and it feels great. On a Momo Race (350mm), I used the 10mm spacer to clear the spokes on the wheel and the button plate. It works, but it felt small on the wheel. The reach on the paddles were a bit of a stretch, but your experience might be different if you choose the larger cf paddles.
Using the Simucube QR and my above setups, I would reccomend the following screws:
R20 Evo - M5 x 40mm
P310 w/ Turn Center Plate - M5 x 45mm
If you don't have the screws, order them at the same time to save on the shipping. Getting it elsewhere is more costly if not ordering in bulk.
The buttons have a nice click to them and love the "Turn" laser engraving on the top of the plate and on the shifters.
Two Funky switches are great. One for the Black Box controls and the other preset commands.
The one thing I would mention is the funky switch is quite low in height in comparison to the button guard. Using bare hands or thin properly fitted gloves, it isn't an issue, but if you're wearing thicker gloves, it might not be optimal.