I think Turbo's are the way to go, not KERS. There should be some detriment to the gain in HP and acceleration/top speed. Like the engine blowing up.
That's a false dichotomy though. It's not turbos or KERS - realistically, it's probably turbos and KERS. The detriment to running KERS is weight/packaging.
Regardless though - this thread unfortunately got sidetracked like so many others.
I think that (getting back to the original topic) if unlimited KERS were allowed, we would inevitably see all wheel KERS, and perhaps even inboard braking/recovery systems aswell. Certainly the methods and technology behind regenerative braking are in their infancy - and perhaps F1 could aid in their acceleration.
One wonders about the weight balance issues aswell. I can expect some shifts in driver position, wheelbase etc. as all the teams jockey for the best combination of packaging and weight balance. We saw already how Ferrari and Mclaren suffered from their weight distribution woes last season - perhaps that's more of what we would see in the first few years of the implementation of the rules.