Well, all that depends on how you define "improving". IMO, a fixed PB 2.5 is already an improved PB 2.5...
But before we start nitpicking here, what heavensoul mentioned IS a problem. While you're right in saying that Pierre didn't want to make a whole new bot but rather fix PB 2.5, the navigation should have changed from the original PB 2.5. PMB implemetded this new A* pathfinder, which resulted in the bots taking different routes and as-maps being fully enjoyable because the VIP also uses different routes. If this feature were suddenly missing, it would indeed mean a major drawback. Does anybody else have this problem? I don't want to mess around with new PB versions right now, because I'm testing and fixing waypoints all the time...