hi ian when you say inline tap is that the one that supplies the water to pole like the one you can have by your belt
Yep!
my flow control is in the van, never felt the need for it on my hip as I can always fold the pole hose and pinch off the water flow if needed, or pop the pole hose off the reel hose (easy enough as I have a rope sash over my shoulder attached to the reel hose, so it is very easy to pop off the pole hose.
Once my flowrate is set, I rarely ever need to change it.
Well maintained your membrane should last at least a couple of years.
Change the pre-filters every few months, keep the membrane frost free and flush for a few minutes before each use, oh, and don't adjust the waste/pure ratio to high either!
Ian