I just finished trying out the version you linked to on my 12" Powerbook G4 (1.5 GHz, 1.25 GB ram, Tiger). It runs great overall; I think it about the same overall speed or a little faster than Safari 4. Like you mentioned in the blog, the HTML5 youtube is pretty choppy. A 1.5 GHz G4 isn't that fast anymore.

My only gripe, that really can't be called a bug, is the following. I use tinkertool to remove anti-aliasing from my display. It works for Safari, but not on TenFourFox (nor any other Firefox). Any idea why? Just curious.