Dry stuff is quite easy to suck up from the edges but compacted damp/wet tile grit moss and sludge well that’s a different story especially if the gap between the tiles and guttering is quite narrow. I've found different types of tile like the ones with rounded sides can be harder to clear under them properly especially if square line (flat bottom) guttering and have narrow gap. Also don’t help when cables run in gutters and large overhangs of roofing membrane in guttering can be a pain in the butt too.
Just wait until you get to do some badly block corners with sods going up the roof valley too. Now that can be fun for sure.
All so say guttervac sellers will not admit they don’t work very well on all types of jobs so you have to look at ways to make your own tools yourself really and even sometimes still use ladders if need be.
I'm sure someone will be along in a mo to say you should have brought skyvac's industrial instead as it's the best thing since sliced bread...Oh the joys of guttervac clearing