Argent Tournement and Faction change
I know in the past when you did a faction change your argent tournement reputation and achievements reset. Is this still the case? and if so why? Wrath is 2 expansions old at this point. Why cant we lift that restriction?
I faction changed during cata and lost my achievements/reps/titles, but got them all back when 5.0 hit. So I assume it's safe to faction change without worrying about it.
But if you're going panda/goblin/worgen you wont be able to do any dailys with any of those factions there if you arent completed yet.
Stood in the Fire
You will still lose your progress and reputation and most of the achievements.
There is a warning when changing faction.
"All PvP and Argent Tournament achievement progress will be reset. "
Unfortunately. I do agree with them as i have did it on Ally and then Horde on the same char, but do look at the light side of it.
More tokens = More mounts and pets
You will lose all your rep/achievements if switching from Horde-->Ally or Ally-->horde.
However, if you have your rep/achievements then faction change and re-grind those rep/achievements you will retain the original set if you decided to faction change again.