How much does level affect EXP distribution when selling leech?

I'm creating a F/P mage to sell leech and I'm thinking about capping him at a certain level in order to sell leech more effectively. However the lower the level at the more I have to spend on equipment to reach 1HKO on Petri. Does anyone know how the exp sharing formula works in regards to character level? Has anyone does this before? Is there any recommended threshold that you would cap your character if it's entire purpose is to be a leech seller?

 

The relevant calculation is:
The XP per leecher is leecherlevel/total party level * half of xp of mob(Which is a flat number based on party size, the mob in question, and the level of HS.)
That means at most each level up is about 0.35% xp (assuming level 150 for kill and 108 for leecher)
If you sell solo/duo a lot this can be quite a number. The difference 10 levels make is the difference between 3.1 and 3.2.