Both PBS and line bidding have their pluses and minuses. Either way if you're junior you're pretty much hosed, as that's the price of being junior. The more senior you are PBS gets better and better because of the unlimited line options. Again, with paper bidding if the company doesn't make a line that has exactly what you need, tough luck. With PBS there's a lot more flexibility the more senior you are. Need the 3rd-7th off with a trip that ends on the 12th before 3PM? Not a problem. Easy to bid it and much more feasible than with paper bidding.

What PSA has with paper bidding + SAP is about a great of a system as can be devised (when it works properly, of course). You get to have line bidding as a good starting point for what you want, and the SAP is essentially a pilot-run PBS system where each pilot goes in and tries to swap for the trips they really want/drop trips they don't want. You can get the important days off that you need and in many respects can build your own schedule (again, when it works right).

The real benefit of the SAP is for the junior lineholders. Senior guys make out with line bidding or PBS, but with the PBS a junior guy can expect min days off, work on weekends/holidays etc, uncommutable trips, and on and on. With SAP even the most junior lineholder has a world of opportunities to adjust their schedule to have just as many days off as the senior people if they so desire. It's really combines the best of both worlds.