I'm going to post because it may help others going down the same route.
Ok so my vac is up and running and working pretty well now. I cleaned the front of a large four bed detatched this morning and a couple of things i've found:
It's fairly critical to get the nozzle angle just right otherwise it misses much of the sludge and leaves clean trails runing through it. A camera is pretty important here if your not going up ladders.
Superlight sections do clog a little as will every pole so i'm going to spray the insides with silicone spray when i've cleaned them up.
38mm tubing has a couple of drawbacks obviously the diameter is a little small and also it is prone to twisting and kinking if you don't lay it straight. The other problem is that the insides are ribbed like the outside only not as much, so the sludge tends to stick to it pretty quickly, the larger grey re-enforced tubing (51mm) has a smooth bore and so would probably be more clog proof.
Set up time about ten minutes, cleaning time around twenty minutes (front only top and garage so about one and a half lengths of the house).
Pricing? mmm well it was my sister-in-law and unfortunately she timed me so i asked her what she would be prepared to pay to have her gutters emptied front and back.................£30

Good job she's not my customer.

PS don't let anyone kid you it's hard work! You can rest the pole on the gutter and inch it along with twists of the wrist. Might be different at three storeys and above.