I just flashed BM3 last night on my N20 125i. flash was super easy took all of about 10 minutes.
I flashed stage 1 93 octane and am running a cat back exhaust, otherwise stock.
This has made a huge difference, power delivery is smoother and more constant, feels like a new car, i am going to flash the gearbox after work today and adjust the burbles a little more so i can annoy my neighbors
EDIT:
I also created my account to respond to this as i couldnt find anyone else who had done this to their 125i