I have a port of Chromium (version 5) on my phone. I don't use it, except for the odd bit of testing, as dragging over the page selects text rather than scrolling. That said, Chrome's V8 runs JavaScript much faster than my phone's native Gecko browser.

As for Chromium vs the Android browser, it looks like Chromium has way more features than even Honeycomb's browser [1]. Though many, such as contenteditable, WAI-ARIA, File APIs and Notifications will be difficult to implement on a 3.5" device.

[1] http://caniuse.com/#compare=y&b1=chrome+14&b2=androi...