Yeah I've just left it enabled, but I don't really run on-demand scans with it. I've thought about enabling UAC, but it will take a bit of fine tuning so it's not annoying as it once was.
I'm also teetering between AdFender and AdBlock plus at the moment. AdBlock Plus provided better ad blocking, but it also uses quite a bit of system resources (up to 200MB RAM), which can really slow down some older PC's and netbooks. AdFender has the same blocklist options (EasyList and Malware) but doesn't block ads/popups quite as well. It doesn't let a whole lot through though, and hasn't let anything malicious through. I figure with AdFender, OpenDNS and the custom host file, I should be good to go. This would likely make more sense for some of my clients who have older laptops and netbooks as well, since running Chrome with multiple tabs and AdBlock Plus was pretty taxing.