I'm switching (at least temporarily) to the Shiira web browser for three reasons:

1) Firefox is the only OS X browser that works with Gmail's keyboard shortcuts, but all browsers run out of memory eventually so a second browser is needed for actual browsing.

2) Safari is great, but the new version (2.0.4) has serious problems with keyboard navigation (page up/page down/home/end keys are unresponsive, and tabbing gives undesired results).

3) Shiira (1.2.2) finally has a substitute for Firefox's keyword searches and Safari's AcidSearch add-on: it is called "custom search engines" and is found under the Window menu. And like everything else on Shiira, it works.