OK, so I downloaded FF4 beta, and played with it a bit. I have to say I am sticking with chrome if there are not some major improvements before the final release. I did a refresh test on several pages, and where chrome is near instant, FF4 takes almost a whole second longer. The orange Firefox bar is an eyesore on the upper left hand corner. I fail to see the need to have a separate search bar from the URL. They did manage to squeeze out 2-3 pixels from the UI vs chrome, which isn't much, but I'll count that as an improvement.
Chrome just makes more sense, I only need to see my favorites bar when I open a new tab. How it takes more resources, but is more responsive is a modern miracle. I love having the down-loader in browser instead of a separate window. And I don't care how much memory my browser uses. I have 4GB of memory. Even when I am doing audio/video editing I hardly make a dent in it, and chrome doesn't take nearly as much as those programs do. I bought the ram, I may as well put it to use! Take all the resources you want so long as you run faster and support more things in the process.
One thing I do wish, is that all browsers were always in the consolidated view that chrome and ff4 have when full screened. There are still places to drag the screen around, if you can have less UI then do it!