Great work.
Only thing is I have yet to be convinced that spraying on tfr and then merely rinsing will clean gutters/fascia/soffits up in the way that can be achieved by scrubbing up close by hand.
I'm with you on this one, Mr T.
My problem has been short bristles and deep crevices.
Here's my solution. It's simply a broom and a spray on the end of a pole.

I've tested it using a VERY modest water flow resulting in a fine misty spray and turning the water:
on - to soak,
off - whilst scrubbing and then
on - again to rinse etc.
It's done a great job of cleaning up behind the gutter and up to the top of the gutter support brackets on my garage. The quality of the work appears to be as good as you'd get doing it up close and personal.
I'm going to put this idea together with Jeff1's idea and, hopefully eventually I'll come up with something of real merit and use to me and others like me.
It's not a high priority as of today, but will be when I get my next gutter job.