It should be that when you hit lvl 79 you cannot cash in any extra XP that is laying around. Right now people are trying to figure out how to not get XP so they can have end game dots have ~900 XP and have those cashed in. So you can basically get less XP but more SP's. Not a huge difference but still an exploit.
So simple solution. Don't allow XP cash in after a certain level.
So simple solution. Don't allow XP cash in after a certain level.