I get where you are coming from. I have the same feeling towards the GTI. My thoughts are that you need to drive your M3 at the track. They only come alive when you push them. The grin will be there, and your face will get sore by the end of the track day. Furthermore, no matter how much you master the M3, IMO I find that it always feels like it has the potential to kill you. I don't get that with FWD cars and that's too bad.
Mini's are great fun.. but.. the fun will wear out. I really do believe this... and I think it is probably true for all easy-to-drive FWD cars and hot hatches. On top of that, as it wears off, you'll realize you're driving a Mini. Sorry. It's just like Miata's are great track cars... butttt... I mean.. you know.
Actually while you're at it, go give the VW a drive and let me know what you think. It was one of the most fun test drives I had ever been on.