the only advantage would be having the appriopriate gears for the m3. with the 2.5s gearing mated to a 3.0, it would actually accelerate faster than a stock m3, but would have a lower top speed. Personally, I wouldnt swap the rest.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>