No new noises so far, but I don't have many miles on the set up. I also have the Delsing Rear Sway Bar Brackets and Bushings a.k.a. 'klunk fix' so I didn't have much of any suspension noise before the swap.
5mm spacers with stock wheels will probably work, but I have not tried yet. My Rota Slipstreams are +45 and there's still a little room left. Longer studs will stick out of the lugnut holes farter if you use a different offset wheel, but with a different offset wheel you won't need long studs and spacers. You need to have a minimum number of turns on your lugnuts and that's not possible with a wheel spacer on the stock wheels. If you plan on switching wheels back and fourth you should use open ended lug nuts so you know you're tightened down on the wheel instead of the closed side of the nut.
I'll be putting some miles on it this weekend, along with an autocross where probably 4 different people will be driving the car and giving me their impressions.