I've never found a roller bridge with low enough friction to work the way we might hope. If they work at all it's because the surface the string needs to slide over is smooth rather than having a sharp edge. Personally, with Bigsbies, I've had the most luck with "rocker" bridges like the ones Bigsby made (makes.) The strings don't need to slide across the saddle; the saddles move with the strings. I've found the same thing works on other instruments with regular pointy bridges that can move a little, provided you're not trying to pull off Jimi Hendrix style dive-bombs.
But listen up, here's the secret: if the guitar does go out of tune with a typical tune-o-matic style bridge, just wiggle the arm (perhaps violently) and it will often go back into tune.