I have deer on my commute - lots of them. I wouldn't be too worried about them hitting you. I find most of them just stare at me as I go by or run away. The only isue I can see would be if you startle one, and it runs the wrong way and crosses your path.. This has never happened to me.

If you manage to hit a deer, the only way I can see doing it is whizzing along with no headlight (or a poor headlight). Deer often don't hear me coming, and when I ride into work at 4:45 am they're frequently on the road - if you don't see them you don't have time to slow down and avoid them.