Don't know why I bother leaving mine on out here where I live. We only get rain for about three months (at the most) per year, and usually it's something you can see coming, like, a week in advance. Leaving them on the car just lets a perfectly good set of wipers dry-rot, so I'm thinking I'll just keep mine in the trunk just in case I get caught in a freak storm, and stick with treating the windows with Rain-X.
FWIW, I never have any glare/streaking issues with Rain-X. Depends on which version of application you use, and how you follow it up; I use a double-application of the Window Wax form of Rain-X (sort of a gel), wipe it off with a wet cloth, then buff it with a perfectly dry microfiber towel. Presto! Now I can see each and every tiny little pit in my windshield from all the road debris it's endured in its 250k-mile lifetime ... but no streaks or glare!