Low dps is a poor excuse for a DF run, as long as you meet the reqs you are entitled to run it. Whoever wants a fast and easy clear must PF or accept what DF gives them.

If the complain comes from a mentor then, to me is sufficient enough to revoke permanently its status and strip him of all the perks he got with it. Hell, I'm going even far more and will delete all and everything gear he have on his account and get him naked, some people deserves it.