Hi Robert,
I tried Purity X polymer sealant a few weeks back and it sheds water pretty well. My side windows cleared pretty easily the other day, just needed a bit of air flow.
I'm still experimenting and haven't put it through a few washes yet but it seemed to do a good job after the detailers used it earlier this year.
After washing it was applied all over the car via a lance and rinsed straight off, so it's really easy to apply to paint/glass/etc.
It needs topping up every 3-4 weeks but only uses a small amount so I hope the teeny bottle lasts a good while.