There's more than tabs, here.
I have been developing CSS right sites recently to test Safari's rendering engine and at the moment, while it is very good, it isn't quite as good as Gecko with CSS. All the normal stuff works fine, but when you throw in tons of <div>s and <span>s with margins/borders/padding/background/position/float/etc. it sometimes doesn't come out right.
Of course, nothing is perfect and I appreciate the challenge of getting all this CSS to render correctly.
I remember David Hyatt posting that he zapped a lot of CSS bugs. I'm anxious to see them.
[edit: the point doesn't really shine through here... basically I'm saying that it isn't interface alone that warrents a total switch. BTW, Safari is my primary browser anyway]
- RMG
Note: The CSS in question is valid and the HTML in which it is embedded is XHTML 1.1 valid...