I have had 85% fitted to my GU Patrol for a number of years now and reckon the following:
1) perfect for Victorian high country (or similar) - at the time I was spending a lot of time in the VHC so installed the 85% just for that driving- crawls up any hill without any crashing and bashing or wheel spinning - excellent for downhill braking - can bring heavy GU to a stop on some pretty steep hills if I want to
2) Have done the Simpson, Anne Beadell, Canning and spent a LOT of time in West McDonald, Pilbara and Kimberley towing a Conqueror UEV490 did a great job - didn't get stopped/bogged on a single dune - again very sedate - no bashing crashing BUT felt the 85% was too low overall - revs were high - fuel consumption was high - but did the job very well
SUMMARY
Now that I have changed my driving profile (full time grey nomad for the last 5 years now and towing a camper) where I am going into more "average" locations when compared to VHC - If someone said to me I will pay the changeover costs for you to go to 65% and I will have your 85% (hint hint) I definitely would
But if I was still spending as much time in VHC as I used to then I would stay with my 85%