I've never listened to the PB10 but have the PB12 and love it... I like it for how it handles the lower frequencies, you really feel it ... it's kind of subtle, it really pulls you in and after the scene is over you realize you've just gotten off a great ride... so far the first canon scebne in Master and Commander is my favourite... my basement room is 10 X 14... I wouldn't consider switching to the PB10 (although I've heard great things about it) only because I've become so addicted to the lower extension of my PB12... it makes want to go and buy more movies... to me, I don't think a sub with better output in mid-base would have the same effect...
cheers,
martin