Dark tachion question

That hidden map in cave of trial 2, where you turn in your dark tachion. I was wondering if that quest had a lvl limit? Me and my friend were going to use it to get quick exp for our infighter. I also heard, that the more tachions you have, the more exp you get, is that true?

It's a level 105 quest.

You can do the quest only once.

And having more Dark Tachion with you does NOT affect how much exp you get. It does, however, take all the Dark Tachion you have with you (even though you will still get the same amount of exp).