All mobile devices are a pain. You obviously haven't tried BlackBerry and Windows Phone devices. Even the best mobile OS in the world (iOS) has annoying problems.
I wouldn't rely on JS for anything on a mobile. JS on mobiles can really slow things down (even basic scripts on older devices).
However, testing on simulators is never anywhere near as good as the real thing.
You might also went to check for CSS3 support on each device: http://caniuse.com
Trust me, there are loads of people out there who would be shocked if they actually tested their sites on real mobile devices.