I've used the fold and pinch method for almost 2 years with the same 60 psi shurflow pump with no problem at all.
Though as my system came from Peter Fogwill the pump box was plumbed to recycle the water when you turned the flowrate down, so when you did cut the flow completley by pinching off the supply, the pump continues to run.
If the pressure is set high then the pump would stop, starting again when you released the the hose.
Works fine.
I don't know if Peter still sends out his systems plumbed up the same or whether he now incorperates the varistream or ecoflow controllers instead...I must ask him!
If I need to raise or lower the pole I will either hold the hose in my teeth
or tie a knot in it
A trigger system works on some poles, but not on the Unger ones because if you have the hose on the outside of the pole you only need to use whatever section or sections you actually need, or even to pop of the brush and clip it into a shorter pole, ergo the trigger system won't work.
Ideal though when you are using composit poles and have the hose fed up through the pole as you are not dismantling your poles all the time, so the trigger is always left on the same pole section.
Ian