I have done a bit of roped work and shot some climbing videos myself.
Personally I am not a big fan of extremely long focals in climbing photography. As you pointed out best angles are obtained hanging at the side and slightly above the climber. If you are able to place your rope close enough to the climber a 24-105 or even a 16-35 are more suited for the work compared to a heavy 70-200, which is quite difficult to handle when you will be swinging around attached on a rope (especially when doing videos).
Of course if you are far from the climber and/or if you need to isolate the climber from background or make details of hands and such a super tele is best suited.
watch gimenez work to see what I am talkin about.BD athlete Adam Ondra on first ascent of L'étrange Ivresse des Lenteurs (9a+), Ceüse, France