Although I use a red dot sight on my CB, I'll wade in and make a comment. If you're wanting to shoot to 70 yards max (I'd certainly not go any farther) I'd think a quality 4X would be plenty of scope. A deer is a pretty good sized animal and a 4X scope should be plenty for precise aiming at 70 yards. Using a 4X scope on a rifle, I've shot groups under 1/2" before, so the aiming and shooting part should not be a problem with 4X, IMHO.
At that range, I'd likely want some type of trajectory compensating reticle, as you mentioned. I think if you were to get a better quality scope you might change your mind about needing 9X magnification. Just a thought.