As others here, I've used glass products for a long time. I used a product years ago called Rainaway, which I think became RainX later?? Either way, as others have said, it just works. And works really good too. The last few years I have tried a number of different windshield coatings, most recent Carpro's new coating Dquartz Gforce. I always find RainX seems to repel water the best. I applied last summer to a car and got distracted by a call, ended up taking it off about 2 hours later. It ended up raining the next day and WOW, I have never seen the rain bounce off or run off the glass like that before, impressed. Now the con with RainX is it doesn't last as long as other products.
I find it actually performs better than the Dquartz, but I know the Dquartz will blow it away in longevity.
For a comprimise in performance and durability I am finding Kamikaze Window Coat works pretty darn good.
There are a large number of products out there, Aquapel is popular, and Soft99 makes a few with there Glaco stuff that works great too. I feel one cannot go wrong with most of them, a bare windshield is not near as good to drive in rain as a coated one. I bought a used car a few months back and was reminded of this everytime I drove in the rain, until I got the time to apply the Carpro coating, now it is so much nicer.
With any product I rarely use the wipers, the products work great. In the end, none of these products hurt the glass, glass is crazy hard, hence why polishing glass (the deep way with ceriglass or such) is so hard and tedious. The only thing you will find is as they wear you will notice the performance your used to as it drops.
