I have to agree with SFIM. I was originally instructing on Bell 47s but then the school I was at changed to R22s. I was prepared to dislike them but we had very little trouble even with hundreds of touch-down autos every week. I always used to carry out throttle chops in the hover and even in the (very few) harder than normal landings which resulted, the Robbie proved itself a much tougher little beast than its looks suggested. The school I was on was a commercial school and I believe that the experience of handling a machine with a low inertia rotor to have been more valuable to students who would mostly go on to fly modern helicopters with low inertia rotor systems. The Bell 47 had more relevance in the old days when students would as likely have gone on to do power and gas patrols in 47s or on to the-then fairly modern Bell 205/212 series.
At the end of the day though, any basic helicopter trainer does the job and it mostly has to come down to economics.