I loved my BBS RGRs when I had 'em - but anymore lately I'd be freaked out with really nice rims in my area - esp since I use my Z as a partial daily driver. The roads and construction sucks.
My input - CSL rep set can be bought 4 times over by the time you buy a set of real BBS LM's. Depending on what you use your car for and how much kitty you have to spend will likely make the decision for you
I think the car looks good in its current form. Black rims seems played out for street cars - unless you have are really 'aggressive' looking car.
Good luck - post pics with whatever you decide!