In reply to Stuck On a Wall:
I think risk of injury doesn't have a very strong correlation with how high the grade is (this is a very scientific observation of course).
I do believe that there are several things which bring injuries across the board:
Not resting nearly enough and climbing often on consecutive days.
Not mixing up your climbing.
Poor technique with not enough weight on the feet and slips which overload fingers, shoulders etc.
Very static style with deep long lock offs leading to tendinitus.
I've seen climbers getting injured because of the above at both 6a and 7a and above.
In fact many top climbers claim they have never been injured - Magnus Mitbo, Alex Megos not until very recently, Adam Ondra nothing serious ever. However those folks have had good routines and habits inbuilt into their climbing from a very early age.