I can live with the close button being on the right, but I strongly prefer the way Safari does it. I accidentally close more than one tab fairly frequently, and while I know and love the "History -> Recently Closed Tabs" workaround in Firefox, it is a workaround for the bad UI of having a close button I don't want to press pop up right under the close button I'm clicking on. I'm not the most dexterous person (to put it mildly), and further punishing my klutziness by requiring precision work with the mouse is not my idea of a good UI.