I have been a swivel devotee since I started WFP. The best for me was a converted Stanley paint pad handle that fits straight onto a Harris pole.
The fist commercial swivels all shared the same fault, the pivot point was too far from the brush stock making control difficult. After raising this with Alex he sent me some proto types to try, I sent him one of my stanley conversions and a prototype of my own. Alex's success in this business comes from listning to fellow window cleaners and what their needs were. The latest Gardiner swivel is perfect.
I would hate to try and work without a swivel, at a flick of the wrist I can clean the glass either with the brush staight or on it's side [ handy for those tiny windows that are not as wide as the brush] And of course swivels are brilliant for cleaning over the coservatory roofs while standing at the side.