Thomas
We do 60ft & i think that is plenty enough, changing every couple of minutes with a 2 man team.
We use Tucker upto 45ft then ionics ergo lite to 60ft.
Tucker do say you can go upto 80ft with 3 man team, the third man has to be on roof with rope around top of pole to assist other two with poling. I personally would not like to go above 60ft without major assistance fom supplier & training to ensure h&s is ok & no major injuries to staff could occur.
The other option is to reduce the size of cherry-picker then pole from that, but same again check with suppliers on max. height. Look on Tucker sitethey have a couple of jobs where this has been done, but, you would need a banksman on the ground permanently throughout job to assist, so thats additional labour.
Hope this helps.
Gary