I've instructed on a variety of helicopters, for a variety of organizations who had differing policies on the use of checklists.
I found that people who use the 'challenge & response' method make about the same number of mistakes as those who have to memorize them. In my view single-pilot ops should always use memorized checklists, as it's poor airmanship to be 'head-down' reading a checklist on a pan with engines/props/rotors running.