I have been to 88ft,
At that height you are at the extreme of controlability, and can only be acheived in a sheltered area.
anythin above that and the pole will be flat against the building and the brush will barely touch the window.
Even at 80ft you will have to pull back on the pole keep it off the building.
There is a good reason why Ionics etc only build poles up to 65 ft, its not the danger aspect it is the stifness which becomes a problem at heights beyond that.