From experience, replica wheels are much heavier than original wheels and will have a noticeable effect on performance, ride and handling. They are also likely to suffer from surface corrosion no matter how well you maintain them. Then there is the issue of them looking different. Have a look at them compared to original ones and there are differences. Those that know (including you) will know they are fake and to me, that spoils a really nice car.
They is a set of brand new genuine Monza Shadows for sale in the classifieds on here that might be worth a look.
www.golfgtiforum.co.uk/index.php?topic=271339.0 It's the worst add ever, but knowing the seller from when he was on here with his Mk6, they will be what he says they are.