Davis system

[O.T.Hill]

I have been using the Davis system (probably not perfectly) for almost a calendar year. Although I struggle with the top of my zone for some reason, it has cured most of my inconsistencies with the low strike. Recently, I worked with a very experienced umpire. When I asked him for a critique, his first comment was about how solid I was and that I never flinched a bit. He then followed that up with his concern that, since my arms were locked in, that I would sooner or later suffer a broken forearm. Since I have started using the Davis system, I have not been hit on the arm (although I expect to). I have only been nicked on the hand a couple of times. What are the responses of those who promote the Davis system to the concern of the exposed forearm.
Secondly, regarding my issues with the top of the zone. I have been told by two very good umpires to concentrate on getting my eyes down to the top of the zone. Using the Davis system, I really can't get there. Any suggestions, other than using the catcher's head to gauge the top of the zone, etc.
Thanks.