Sorry to say Martin, but this is not completely correct.
PAP is awsome in it's muliti tier plan handling, but the problem is that it is dangerous to use when you use paypal. Before you know it your paypal setup in combination with pap gets blocked and/or cancelled.
Of course it's not PAP fault or qualityunit; it's just dangerous to use multi tier setups with many payment processors; including paypal.
Just to inform; nothing else ;-)