I believe you "lose" the concavity look when you paint the Miro's black, at least from a distance. When it's all black, you can't really tell if the wheel is concave or not if you're looking directly at it. You have to sort of look at it from the side.
I have 9.5" Miros all round on my 550i and I love them in the silver finish, I wouldn't paint them any other color. IndyRed is one of my favorite M5 colors and your car is one of the best looking I've seen. I think it's one of the cars that I looked at, that made me go for the Miro's
P.S. Silly question but, do they sell the IndyRed in US only ? (I suppose the Indianapolis in the name kind of suggests it...) I've started looking around for an M5 to replace my 550, but I haven't seen any IndyReds for sale here in Europe