I would stay away from certain flies for beginners, starting with either the Adams or Parachute Adams. I just think that two hackles are much too difficult to deal with when you are struggling with one. They used to always start beginners with the Adams and I never understood it.
Good point, though I must confess that I only tie in the grizzly on my para-adams. It's a good deal of an increase in the time per fly, and the pain in the rear factor to use 2, and the fish couldn't care less...at least...the ones I fish for.

On the catskill tie, though, I do use both.