the stats look good on mine as well, with an RPM higher than the contextual ads. but i've had IBA switched off for months and months.
does that mean i should switch them on?
maybe... maybe not.
even when you switch them off, you still get IBA ads if the user has previously interacted with an ad. (that's how i think it works... not too sure.)
so the IBA's i'm getting at the moment are more likely to interest the user than the ones i'll get if i switch them on -- because the user won't have interacted with those at all.