Although I don't elk hunt, I would suggest a small Sony digital/tape or straight digital/mini dvd depending on your budget. I have heard that the bow mounted camera is very hard to get good shots from because of the vibration at the shoot. they do pretty good before the shot and I guess would be okay for shooting teh pass-by animals. If you wanted to shoot your shoots I think it would be lacking. If you arnt hiking that far, you could use the mini Sony on a small lightweight tripod, one that is quick to set up. Most of the small camera (Sony and others) come with remotes to start and stop taping making it easier to use when game animals get close.

For whitetail stand hunting, I use my mini Sony on a camera arm hanging next to me but, I see whre that won't work for the hiking elk hunt.
Best of luck in making a choice. I think the filming would add a great deal to your hunt.