1. PB released update on 11/30/2010. That added some more cheat scans, at least the few one which I submitted is detected.
2. Sure PB add lags but it works as anti cheat with PBBans scans.
3. People will always lag, if they have old PC. Sorry to say but I get stable 125 FPS on any server if host as nice BW.
4. Some people will always lag, because they run tons of things at the background.
5. Without PB how XP save works for you? No PB = No GUID = No XP save.
6. Alternative is use Etpro + SLAC! Best!

People said less cheaters on 2.6b. So I run server without PB for few days on 2.6b for testing. As soon as I turned on PB, more then 4 got busted in just one day.

You might want to ask your members, about what PC specs they have, when they get lag, is it FPS lag or hardware lag or internet lag? Many things can cause lag.

It will be either PB or 10-50 FPS less. I would rather play on PB server rather then non PB cheat fest.