I haven't read the whole thread yet, I'm going to go back through it now.

However, I wanted to say that the 1k instance clears requirement to me speaks less an "experience" requirement, and more an "attitude" requirement. Like people have said, most of the runs in your 1k total going to be grinding endgame dungeons for tomes, not leveling dungeons. It's not about knowing the dungeons well. Rather, it's about how long you've been playing and what your attitude towards the game is. Someone with 1k runs is going to have been subbed for a while, likely over a year, and has stuck with the game for a long time, rather than quit because burnout. They're clearly patient, passionate people who love the game and what it has to offer. Those are the people you want being mentors, because they're the most likely to leave a good impression on new subs.

My $.02