It's not the manipulation of the device(s) that is the problem. It is the splitting of your attention between multiple active thought processes (as oppose to passive, like listening to the radio) that does the damage. The human brain just doesn't multi-task despite what folks would like to believe. If you want to use the watch for taptic notification to pull over and check a message or email, fine. But don't think it is any better than hands-free calling or fumbling with a phone (as you elude to) which are equally bad. When you're driving: drive, and enjoy a respite from the need to communicate with others not in your immediate vicinity. Pull over if you just have to talk right there and then.