i find as i get nearer your age
my shoulders really ache, so i thought if they were cheaper enough i may invest in some and wfp is ok for straight forward connys there is some with really weird roof shapes
....so there 
I know what you mean Bob, the older i get the less i like cleaning conny roofs & gutters/fascias ,
My solution is, once a custys roof has been cleaned i offer to clean it every time as part of their mantaince window schedule.
Medium size connys, with easy access all round would be an extra £5 and larger ones with limited access an extra £10.my normal cleaning cycle is between 6 & 8 weeks and i find most customers take me up on this, as there not dirty after this period of time,
Its just a quick scrub & rinse and stops that shoulder knackering clean every year or two.
Give it s try on one or two & see how you get on, it dont take long at all.