I was actually thinking the same thing (as edesign), and I got a headstart (like apparently some others here) and decided to give Safari another go with 1.3. I'd forgotten how snappy some things are. And how nice in-line spell-checking is.
The main thing that annoyed me with FF at that particular moment is that I found that occasionally, FF would make entering text in a textbox (like replying to this message) *painfully* slow on my G4/800 iBook (which, admittedly, is not exactly the Aston Martin Vanquish of notebook computers). The thing is that the slow typing was NOT a function of...how many tabs were open (at least, closing other tabs did not make it go away), how many other apps were open (ditto), and rebooting FF did not always help. I've heard other people complain about this. Is there an effective fix?
Back to FF and Safari... things that matter for me (mostly dittos to the always insightful Mitthrawnuruodo):
In Safari 1.3's favor:
- Some aspects of the user experience are surprisingly fast
- Better keyboard shortcuts in some places (the tab switching is easier on the hands and more mac-consistent)
- Seems to be less of a memory hog -- at least, if I go and do something memory intensive, when I un-hide Safari, it seems to have to page in a lot less stuff than FF did
- In-line spell-check

- Acid search's new search site process is not quite as streamlined as FF's, but it does let you add custom sites much more easily than writing .src files. In addition to most of what I use on FF, I was able to get a version of PubMed that uses my school's EZProxy log-in and gives me full-text (from home), and I was also able to get Fed-Ex, UPS and USPS tracking in there, which I don't think are available for download for FF (maybe I shouldn't be so lazy, and I should write the plugins!)
In FF's favor
- As said before, the tabbed browsing experience, esp if you use TBE, has so many more useful options in FF. I especially miss...Apple-Shift-Z to unclose a tab, the ability to re-arrange tabs, and as Mitt said, a warning when I accidentally try to close the whole multi-tab Safari window
- Adblock really is better than PithHelmet, esp. considering no one wants me to pay them any money for it...
- Some sites have rendering issues in Safari 1.3, such as the Friendster example (not that I really go there a lot...I've gone there more in the past few days, to confirm for people that there's an issue, than I did all year!

)
Well, though, I think Safari might be winning at the moment for me, again. But, besides Camino, don't forget, FF 1.1 is due in about a month, and better MacOS experience was on the priority list!
