At vet 5, if it gets there, the CmdP effectively wins games just by being around. Infantry bonuses on grens or MG's is amazingly powerful. (Before saying don't let it get vet 5 I would like to point out that a binomial situation in which the question: Does he have a CmdP at vet 5 -> I lose, if not -> I can still win, is extremely poor game design).
before you use that as a balance argument i'd like to remind you (don't have the quote on hand) that bC said that if space marine go to t3 and shit out terminators against eldar they deserved to win.