I've championed swivels for years, in fact, I pestered Alex Gardiner to finally have a "proper"one manufactured (we used to have to use modified broom swivels before). I couldn't work without one for sure, IMO they are as important as the pole itself!! You don't have to move your body half as much either when using one.
I use both as I like the carbon necks and the swivels
never tried