I extensively test my webs manually on basically all relevant browsers, up to few old versions, and on different OS' and devices. My conclusion is that Chrome on Windows 7 is by far the most 'snappy' and Firefox on any OS most 'dev friendly' (even though Chrome is coming along that way very nicely). That being said, Opera on mobile is very fine, but I still prefer using whatever stock browser is on particular device.…
There seems to be documentation here: http://www.opera.com/dragonfly/documentation/remote/