Gosh, previously this thread is interesting and take many peoples minds off PR1.2 or makes the PR1.2 thread cooled down.
But now, I think, need PR1.2 to cool down this thread :P

Nonetheless, I believe there's always risk, but I notice something.
Having the clock speed at 600mhz max, the moment I go online, the clock speed hit 100% for quite some time, and it lags.
Seeing this situation, would OC actually helps and reduce the "load", and thus clocking less at max clock speed?
Example:
Let's say 600Mhz @ 10 seconds
When OC to 900Mhz, probably it only need to run for say 3~5 seconds?
Just a wild assumption.
If true, I think this actually helps rather than cause problems?

But on the other hand, if talking about running apps which constantly occupies high processing power. Thus, running @ 600Mhz VS @ 900Mhz for long period would be a different story.

Finally, I also wonder if one of the reason the limit of 600Mhz is also due to the reason of Battery? Since the N900 only comes with 1320mah battery and there's issue with how long can the battery last, possible that they try not to clock at higher speed so that the device is able to have longer operating hours per charge?
I think it could possibly be one reason?