besides the fact that people hardly EVER read the posts above them and barge straight from the OP to their own $0.02, this post is FILLED with wrongness (and a little rightness).
as mentioned before...
...you DO NOT GAIN CHARACTER XP after 50
...you DO, MOST DEFINITELY gain legacy xp from characters at 50.
and that's my $0.02...paid in Canadian coins!
Legacy XP has a cap, though.
You can gain legacy XP at 50 just fine, but when you hit the legacy cap, you stop earning it also.