I've had a 2013 135i M-Sport 6-spd for a couple of months. Years ago I had a 2003 G35 Coupe with the manual tranny. My wife currently drives a 2010 G37x sedan...nice car.
The 135i, especially with the 6-spd manual, is in a different class. The n55 engine is a work of art...sounds so much better than the coarse G37 engine. The G hauls butt, but the sound is not my cup of tea. I also have the BMW performance exhaust and that is an incredible addition....sounds fantastic!