If you are doing it right...don't regular bells at least touch the forearm when the arm is up? Correct form can reduce the impact...but I don't think it can eliminate the weight against the forearm when the arm is overhead.
Deanne, I think I'm like you. I found that even if there is no impact, just the weight resting against the forearm hurts, a lot. (I even had my hubby gently set the bell into my hand so there was NO impact to see if it was just the pressure from the weight...and it did. It hurt and left a bruise. Guess I don't have enough muscle on my forearm, it is bell against bone.
I hadn't heard of contoured bells...sounds interesting.