I can understand when paint would be better, if the wheels have date-stamps/part number or whatever which are visible and it's a show car then powder-coating will mask these marks slightly. If date stamps are important then go with painting.
If you use the car for what Audi intended and use it then I'd go for powder coating.
Also if the wheels have any sort of pitted corrosion or kerb rash then PC will fill these blemishes(just hope that they've had these bits well blasted prior to getting coated!).
I had my early style Speedlines' powder coated and lost the wording a bit on the spokes, also the metal centre cap didn't fit right after powder coating due to the extra thickness.
If it's 10-spokes just rattle can them, no need to mask
Just my thoughts
