I've used Cachy for about 2 months, having used Arch for a long time prior to that.
It just feels a lot faster (anecdotally) than Arch. I don't tend to play a lot of games either, but for tasks like web browsing and watching YouTube, it feels smoother. I don't think I'd go back to Arch unless Cachy did something really stupid to mess up which I hope they won't. No point in leaving free performance on the table with little downside.
Also you should never need the AUR. I've never needed it for anything in years, so the malware attack wasn't a concern at all. Yes, absolutely do switch away from Windows.