My 330 has them. That plane is a few years old and was using only one 8411 per elevator so it might have been necessary (it was like that when I bought it used). I was contemplating doing it in my Yak but I figure I'd do it if I felt the need. Running one 8611A per half and I don't have the need.

Just be careful as you can add tail weight here as well as putting more mass further out from the centerline which could slow down snaps and/or make them harder to stop. I'd try it with out and add the counterweights later if needed.

........Mark