I'm always using tucker brushes and go over the frames all the time, so no probs cleaning in the rain (apart from the odd customer which we all have
). I bought a new mono filament Vikan a couple of months ago, tried it using cold WFP water and threw it in the shed. Did not like it one bit. Re-tried it again this week using hot WFP water, not bad at all. Scrubs slightly better than a Tucker as it's firmer bristles and sits against the glass better. Feels unusual after using Tuckers for so long now but getting use to it.
Funny how we get use to certain brushes and don't like change.
Every now and again I make comparisons between brushes on different types of windows to see which works best on what, ie. dreaded leaded's, sash, flaky frames, etc.