you wont miss your M3 once you're holding GTR wheel, which i dont think is necessarily a good thing.
assuming you're not quite often into track, i think C63 would also give you greater pleasure. For daily drive, it's responsiveness and big accelaration that all matter, isnt it? But it's not recommended either cuz that's all you got and that cost your a good look (dont you think so?) and fuel and the time you waste for fueling which is really fucking annoying and it's chronic as long as you stick with C63...
My suggestion is either to get a GTR (sure then you're gonna be bored by any other supercar) or to see what's next gen M3/M4 like.