While I haven't used KAIO on a windshield, I have use ZAIO on a windshield. And yes, while water does bead and stream up, it did seem to me that when it did become necessary to use them, the wipers did not seem to get a good "bite" on the windshield. It was like they were skating over the top of the glass. I assume due to the ZAIO.
So, I'll continue to use ZAIO on all windows save the windshield.