35+ years and shoulders are in A-1 shape. I did once have a tiny but brutally painful rotator cuff injury (I swear it was the result of a poorly placed flu shot!) but fortunately got relief with only one cortisone shot.
For those of us exclusively reliant on our upper extremities for mobility, you've got to think LONG TERM. Many wheelchair sports may be good for the soul, but the repetitive stress is the piper that will want to be paid.