I personally dont like the restrictions that xp systems put on you. As a player you should have the freedom of choice to choose which job you want to be.
I guess you could use job ranks system to replace the XP/Level system. The bad thing about XP/Level system is that u can't really control the server as the playtime does it. With the job rank system you can remove players, remove xp from players and such, and then make less jobs but with variants.
It depends on what gamemode your using xp systom for. Xp system is good for scp-rp and thats all i know/played in the past and seen. I would not recommend xp system for most RP gamemodes.
