Here's what I know:
PMC comes in 75ml only.
It's availability is unpredictable. Last year, it was off Chanel's website for a time, and scarce in stores.
It's a masterpiece; a Polge triumph.
The original Pour Monsieur is apparently still in production, and offered in Europe, but I've never seen it on Chanel's U.S. website or in stateside stores like Sephora, Saks, or Macy's. It's more of a classic cologne than PMC and both versions have their fans (often passionate of course). I prefer the Concentree. As for Egoiste, I'm not a fan so I can't comment.