Its a good idea mate, but I have already done the majority of the job, the lower level guttering at the sides and rear of the complex, I actually used a similar method, although I didn't use a hose, just an 8 ft rod with a bung fixed onto the end, I kept pushing the rubbish along the gutters, and then clearing it out every 25ft or so, it worked well.
I have to use the guttervac for the high level stuff, as I stated it in my method statement, and the residents seem quite excited about it for some reason!!!

Hopefully going to be using the guttervac on wednesday, so I will post some pictures and let you all know how it went!!