Helmet,
I have experienced the pitch up phenomenon around 3 or 4 times in my 2500 hrs BK. All were during IFR operations and normally preceded by a bump due turbulance.
It is quite an insideous little problem that once started you need to react quickly before you go past 20 degrees nose up. When it first happened I put in a correcting input that just wasn't enough and felt as if I was chasing it all the way to the stops.....
It dosn't take long before you can pick when it is going to happen and apply a decent correction to snuff it out.
I normally fly around at 60% tq and matched about 98%nr due to the cycle count issues. Usually we are at Max T/O but only around 4000 DH.
I believe the child flight guys in Sydney (oz) had a ripper of a nose up situation that gave them all the willies.
I have not experienced the problem in any B2's I have flown.
Cheers