You can't just take into account the weight of the brush and think its only 4oz heavier, its not worth changeing.
Fact you do not need to pull a salmon brush off the window to rinse as you have to with the vikan.That puts a lot less strain on your arms. The higher you go the easier it gets.
The salmon is a rectanguler shape so is more suited to rectanguler windows, the 10" Vikan is oval so it does not glide into the corners of the glass the same.
I find the density and shape of the bristles of the salmon brush far more suitable to clean frames above the glass. Its far better at removing spider egg sacks on first cleans then the vikan.
The difference in weight between the brushes is accentuated when working at hight, the greater the angle you work at the heavier the vikan brush gets, the higher you go the heavier the vikan gets. If you have a long gooseneck so the brushs weight is further away from the pole or gravitys center then the heavier it feels.
I have had a lot of problems with RSI since i went WFP at the start of the year, loseing manys nights of sleep beacause of swelling in my hands and mind numbing pain around the tricep muscles and elbow joints. I switched to the salmon brush 9 days ago and I have had 9 good nights sleep, the tingling in my hands from RSI injury has nearly gone.
For me The Salmon brush v Vikan brush is a no brainer. The same could be said between 1/2" v M/bore hose.
Nel.