Wondering if there is ever an issue

with getting the edges of glass or frames with waterfed poles. For instance, does the brush easily wet and rinse the very edge of frames or panes, or do you have to kind of work the brush more when getting edges?

Yes you have to pay a little special attention into the corners and edges. keep in mind too that most brushes have the jets coming out around 2/3 out from center so when rinsing you must remember to either overlap the side fames or point the jets towards the edges for a good rinse. Also some windows have silicone residue along the edges which require you to pay more attention there. Just part of the learning curve.

Scrub, scrub, scrub Rinse,rinse, rinse