Do it. I had an Interlagos Blue Z4M Coupe for 2 years and if I didn't have kids now would still have it. The 335i was the closest 4 door I could get (without spending £££ on a newish 4 door M3!) but the engine on that M is night and day when it comes to comparisons. It's like an animal that keeps goading you to go further. Combined with that chassis and drive train it's a wonder.
Seriously do yourself a favour and try one. You have to learn how to drive again to a certain extent but my god is it worth it. Roadsters look good but for future classic and higher residuals save a little extra for the coupe. I'll be returning one day I'm sure.