Hi
IMHO it may be more difficult to use in practice with the 90 degree brush mounting. Working at an angle to the side you would need to hold the pole more securely in your hands as the brush would tend to want to 'fold under' on the upstroke, especially when cleaning a center transom bar and the top of the window.
I've got the Mk2 swivel sold by Gardiners fitted to another brush which is fine but TBH hasn't been used for a couple of years now. But I don't have any windows behind concrete pillars on our round to contend with.
For the couple of times a day when we could use the swivel, ie windows above conservatories accessed from the side, we find that turning the brush sideways gets into the corner ok.
I couldn't envisage this becoming something you would use all day, everyday and so ask if you would tie up a brush and go through the drama of swopping to over for those couple of windows.
Spruce