Horses for courses really, and I think it is better on some colours than other for sure.
My mate currently has a MkIV black Golf Gti 3dr on 18" RS4's and has rediculously dark glass from the b-pillar back, and slightly lighter and possibly almost legal tint forward of the b-pillar.
It looks complete class in my opinion, without even a hint of boy racerness (we are both 35 now and not getting any younger).
To be honest with two tone leather seats it would be a shame to hide the back, I was just hoping to find a pic of factory fitted p.g. on an S3 so I could decide either way.