I like Tool's 'Anemia' and APC's 'Thirteenth step' the best. I have just about everything from both bands catalog. Funny, there's a few PCircle songs that strongly remind me of PTree, but overall the only similarity is the contrasting heavy and quiet interplay. Tool also uses that interplay to good effect.

Shoot me your address woodya 3lb, I've got that IQ disc to send you and can include some Tool and/or Perfect Circle.