i have a e92 m3, a m5 , and a GTR and i can tell u that the m's are tame compared to the gtr. nobody even notices them but the gtr turns heads,cameras,videos.
The only bad part is that i use the m's as daily drivers and use the gtr on rare occasions so i dont put miles on it.
What gets expensive is modding the car as oem ones are beginning to look tame to me.
Best of luck. Money wise its much smarter to keep what you have.
I am a little surprised on the responses i have seen many past similar topics and many of them are so pro bmw that its unbearable to read.
i have seen stupid comments on e46fanatics that people stopped caring about gtr's in 2009 and how they beat gtr's at the track all the time. lol