Helm of the tracker quest should be giving a decent amount of EXP on hand in:
Alla comment link #1 : "I got the 4 heads at 54 and waited and finished when I reached 55 and got half a blue bubble xp at 55 for quest completion."
Alla comment link #2 : "i handed in the 4 heads in POg got atlmost a blue bub at 60 "
Currently there is no exp reward.