The Camino guys just have higher quality standards. IMHO Camino alpha releases are often so good that they could be called final releases.
The one guy hired by MoCo to work on FF for Mac is currently not working to improve the Mac experience. No, he's working on not sucking even more.
Gecko/Mozilla Plattform 1.9 will use Cairo which up to the latest FF3 alpha works really really bad on Mac OS X. If you think that FF2 has issues on Mac, you should try that alpha release. It's horrible on Mac. You get Aqua buttons but that's about it. I know, it's an alpha and alphas are allowed to suck, but right now the current builds of FF3 don't even display many italic fonts. Think about it: The FF Mac guy works almost exclusively to fix Cario bugs on OSX. He's not working on Keychain integration and so on.
So for the final release we can be lucky if FF3 won't have MORE bugs on OSX than FF2. You can expect that italics will work again, that arabic text will work again, but actual improvements in the Mac departement compared to FF2? I highly doubt it.