Built mine in June, I hire a Nilfisk but will be having a good look round Carpex and Windex, especially Omni gutter vac and Ionics gutter keeper (again) Yes the wear does worry me hence the testing but the results I got are really concentrated- lets say a 30 X effect.
I mainly use swivel brushes and use something different to ptfe, you do need to really twist the pole from the ground without spinning to get the required angle, have you tried a swivel brush ?