Not sure I agree with health on kill. Unless they're support bots, dead bots drop money, and money heals the Scout. It'll even overheal (to massive amounts), where health on kill won't. So basically, if you kill something to trigger health on kill, you're going to be picking up cash and healing anyway. Money better spent elsewhere, I think.
I'm on-board with the other suggestions, tho. Maybe some bullet resistance if you're having trouble with Giant Heavies (since they have the best target tracking-- it's perfect, or nearly).