Will be interesting to see if you stay with the GTR, I bought a GTR about 3 months after i sold my 2008 M3 (2009 GTR) and kept it for about 6 months.
I'm not trying to make this a GTR vs M3 post so i'll leave it at that!
You are 100% correct in the fact that GTRs get WAY more attention/looks than the M3 and it's not even close on pull from launch. Heck i even drove an American car (gasp) CTS-V for a little while and the GTR butt test felt much faster than even that beast!
Again congrats on your GTR and who knows maybe we will both be lured back when the F82 M4 comes out (mmmm modding a TT i-6)
In the mean time enjoy your GTR and I'll modd my 550i and drool at the M5 lol!