The comfort and convenience of a p-valve are awesome. Once you've dived a drysuit with one, you'll be reluctant to dive a drysuit without one. Doubly so for a tec dive; immersion diuresis always gets to me by the end, and I've felt my back teeth floating one too many times. Given the choice between ripping out a few pubes while removing a condom catheter or feeling my bladder bulge while I'm desperately trying to peel off a drysuit, I'll opt for for the first anytime.
Re: plastic zippers, they've improved over the years. If you'll look back at the Scubaboard archives, you'll see complaints when plastic zippers first came onto the market, but those gripes have pretty much disappeared. As for me, one of my drysuits (that I bought used, BTW) has a plastic TiZip that I simply luuuuurve. It 's flexible, glides like a dream, and requires far less labor to lubricate than a metal zipper. Plus, that plastic zipper has lasted longer than some of the metal zippers I've had in the past.