Rael is plagued by MSIE instability on Mac OS X. I use a recent nightly build of Chimera as my default browser. 0.4 has some issues with plugins (or with QuickTime anyway) on 10.2, but the 0.5 builds are working great. Fast too! Mozilla is ugly. MSIE is slow and unstable. Opera (on OS X) doesn't render too many pages. OmniWeb and iCab are not keeping up. Chimera rocks.
I have used ChimeraKnight to do the updating. It also makes a backup of the old Navigator and shows the recent change log. Very neato AppleScript Studio application. (With a bad name though...)