Have just completed spraying my fences with the B&Q Sprayer.
VERY fast and no problems with blockages etc. I used B&Q's own stuff that is designed to be sprayed - apparently the non-spraying stuff clogs the sprayer.
However - the spray does tend to go every which way with even the slightest breeze so would suggest covering all plants in the vicinity and avoid spraying near the top of the fence, especially if your neighbour has nice new decking !!!!!
Terry W