I twink all my characters in perfect augmented gear at 49. I have over 1800 cunning on my operative at level 49 at the moment and can hit 4.5k with hidden strike. I have around 16k HP.
I don't think I've lost a WZ since I hit 49.
I don't leave WZs at the end to avoid exp, though. I just want to make that last level of lowbie pvp hilariously fun.
That's a little different to hanging at 49 forever because you can't handle 50 however. The ones that hang there seem to be really bad at the game. That's no surprise though really.