I've updated jquery.mobile.iscrollview (1.2pre1) and it's a very significant performance update. So, you might want to give it another whirl.
This gives you native-like scrollbars (disappearing on iOS, non-disappearing otherwise), as well as pull-to-refresh (new).
Overthrow gives you scrollbars if the native support supplies them (iOS 5). On iOS 4, you get polyfill scroll, but no scrollbar.