rc3 is still too slow for me (19 seconds to open the program completely on my N900), and without flash is useless on many sites.

It seems the only compelling reason to use it instead of microb is if you are a Weave user (and don't need flash).

That being said the devs are doing a great job it has definitely improved a lot in recent weeks. I look forward to seeing where the authors take it in the future.