I dont know about just give the exp to another job, but for me its better have another bonus bar apart form the rest one for that. So lets see you do dungoens with your 60 and gettin more and more of that bonus bar.

Im no totally ok with your idea because, its goin to be slow, but people can take their jobs to max level without know how to use the joband we have a lot of those people already xD. At least with another bonus Bar they going to level faster but they need to use it.