Nissan GTR is competition for the 977TT and is out of the M3's league
The C63 AMG is also well out of the M3's price bracket.
As for the RS4 we will just have to wait for some actual comparisons until then everyone needs to relax.
light steering feel and single piston brakes were both issues with the E46 M3 which you love so much. Personally I think its a non-issue.