I've had the chance to enjoy dual-core android phones (Atrix, 2.2) & tablets (Xoom, 3.1). The difference compared to single-cores is gigantic, everything is super smooth, on the level of the iPhone/iPad as far as responsiveness goes for apps and home screen. I have to say that if the goal is to have a superb OS given a powerful enough phone, the goal has been met, with one (critical!) exception:
Android's Webview unfortunately requires a rewrite from scratch. It just doesn't work as soon as the webview is more than a static page. Css Animations don't play anywhere near fast enough, there are furious hardware acceleration glitches whenever the touch keyboard pops up, touch events are slow as hell, etc.
The article only touches the surface of the problems with the Webview component. At this point we don't care about scrolling. since one pretty much has to hack a custom Webview component just to avoid all the hardware glitches, display artifacts, buggy input handling, terrifying variations of performance from device to device...