People leaving trials/dungeons after leveling should lose that XP.

[MajinSoul]

Sorry to say this.

But blame to the dev for making Healer hard to find.
Because when I play Healer, when DPS leave duty. I get another DPS very fast.

I think 30 mins penalty is enough.

This. It's only an "issue" because it was the healer leaving. Nobody cares about your dps leaving because they get refilled before you even notice they're gone. Instead of increasing the punishment (read: there is already a time penality), decrease the time it takes for a healer to refill as in make the job more appealing. The 5.0 changes helped a lot with that /s