I spent three years on the SIG and believe me you DON'T want PBS. What Dan'l Larusso said is absolutely correct, the system will take senior pairings to build junior lines. There are no "senior" lines, nothing to look forward to as you make your way up the food chain, just a whole bunch of crappy lines that you don't even get a chance to preview before you submit your bid. No prior planning with your home life about scheduling days off--you may or may not get 'em. At least now you can avoid lines that absolutely don't work for you, it'll be a crap shoot if we get PBS.
PBS was one thing that Cheever stated publicly that he really wanted. It does everything for the company by saving money--no SIG anymore, at least not funded by the company, and nothing for us. It's certainly a way to get around our vacaton policy. You bid the first week off using 7 days of vacation and on day 8 you have a nice big trip.
As far as other pilot groups liking this, they all say they like it because they have control over the parameters for using it. If there's one thing I've learned in 20 years here it's that the company will NEVER give up control of scheduling (or anything else).