I know a guy who used to come in to our store. He had a mechanical valve put in 20 years ago and he's great. He even let some of us listen to it, you can hear a faint click-click but he says he has never noticed it. I guess they're really dependable and last just about forever.
Mr Bright-if you do if fact get a pig valve, there's no sense wasting the rest of the pig-I've got a secret recipe for BBQ sauce--a little potato salad, some corn on the cob and we've got the makings for a party when you get out. Good luck