In reply to needvert:
> Given in guide mode the ATC guide can be a dog to pull rope through with the rope running over one carabiner,
Having used the ATC guide with lots of different ropes and krabs over many years, I think you might be doing something wrong, because I've never found it a problem. It helps to be a metre away from it so that the ropes are relatively parallel, so it doesn't work too well on constricted belays.