As luck would have it, I bought a set of second-hand wheels & tyres from my dealer to use as spares for my racing MINI - but he only had some silver ones in. As they were cheap, I bought them anyway, so I might be the only person here who has seen his car on both on a regular basis!
I thought they wouldn't look as good as the original white ones, but to be honest, they look just as good as the white ones, so I shouldn't worry. As far as cleaning goes, both sets are too new to tell, they both come up pristine.