It's back to OmniWeb for me!
So, after a good solid several months' run with Firefox, the constant CPU drain finally got to me and I've gone back to OmniWeb.
Firefox was regularly tops in the usage list, and usually sits on about 33% of my CPU and a solid majority of my 1GB of RAM—which makes my already-slow 867Mhz machine feel like 300Mhz. That, and I haven't had much time to play with GreaseMonkey for awhile, which was my main reason for switching back to Firefox. So, it's back to OmniWeb for me. And man, already this PowerBook feels like it's been greased and waxed.
(Yes, I need a new machine. But that ain't happening for awhile yet, and for very good reasons.)