Wipper juddering used to be my nightmare, whatever I can do, I did, until the extend of using thinner, vinegar whatever whatever to clean the glass - problem persist. I have bought almost ALL glass polisher/wax whatever whatever, even use newspaper to dry it. Some solution will work for a few wipes, then it failed.
Why? There's a chemical layer on our windscreen which smoothen the wiping process. After using Rain-X, it will react or 'change' the chemical on the windscreen and causes judder. This will also happens without Rain-X... after thousands of wiping. How long this chemical layer lasts depends on usage or how good the windscreen is made/polished.
To restore this new and smooth windscreen, you will need Cerium Oxide to polish your windscreen -
Cerium(IV) oxide - Wikipedia, the free encyclopedia . I have been hunting up and down for this item, but it is not easily available locally. Perhaps you should try windscreen replacement shop or other similar shops.
A lot of Singaporean finally solved the juddering problem which haunted them for yearsss by using Cerium Oxide to polish. As for me myself, I bought a set of PIAA silicone wiper (which is a mixture of rubber + silicone, which doesn't last as long as 100% silicone based wiper) and now it can wipe silky-smooth even when the windscreen is dry.
Try google wiper judder / skipping and cerium oxide as keyword. I lost the thread URL. Ebay.com has this powder for sale, but anyone willing to order to try?
Just my 0.02.