Maybe I haven't been imagining the detrimental effect of RainX on my windshield wipers. I always had the feeling that it dried out, or hardened the rubber wipers. Seemed like they got hard and then dragged across the glass instead of having a smooth glide when they were new......as if they had a shorter life than when I didn't use Rains.
At any rate, I don't think I would use it on an expensive unit.