I'm sorry, I don't think this is the way to go. You should reward the player exping at a level lower than theirs to help others out. Giving a 50 an incentive to join a lower level party rather than a 45+ party helps out the lower players, and keeps those lower levels playing longer, as they find it easy to set up a party as all these friendly level 50's just join up whenever they shout.
Why do you want to allow people to help out those lower leveled than them, yet penalize them for doing so?
I wrote quite a bit about this in another thread, but the highlights were this:
I just don't see the point of Level Sync if there is no incentive for higher levels. I would rather wait for a party in my range than sync down and I think many others are the same way. Even in mog's situation, you'd get bored of it after a while of trying out the new jobs at lower levels, and stop.
