The M3 has always been about balance and in my opinion having owned all generations of M3 the E92 is close to being on the limit for public roads. I always felt this car would be dangerous with more hp. Too me it's the chassis engineering that makes or breaks the relationship between car and powerplant. Interestingly BMW always hits it spot on every 2nd generation.
My E30 obviously was amazing but could have handle slightly more power although this probably would have ruined the car (the 3.5 conversions on some cars showed this).
My E36 (euro-spec 321hp) was always a little ragged as if more time was spent on the fabulous engine than the chassis and the car never quite felt 'together'.
My E46 was perfectly balanced in terms of chassis/power output.
My E92 was all about the amazing engine, chassis was great but never had the same balance feeling that the E46 had in abundance. It felt big and heavy when pushed round a twisty Scottish road.
My E82 1M is more like it but it takes a while to get used to the sudden shove of torque that you get when the turbos come on boost, the chassis is so forgiving though and its much closer to the feel of the E30 & E46
These are of course my experience of these cars on UK public roads and tracks. You may have your own experiences.
So simply the M3 is in danger of becoming the junior M6 GT type of car with too much power that will move it out of the class it created in the first place. The M3 was never meant to be a big HP car - it never was - there have always been more powerful rivals - the M3 was always all about FEEL and BALANCE. Sadly having seen the new F30 - which is HUGE - I think the purists will have to turn to the next gen M2 for this type of experience as the M3 will move up to a different slot in the market.