* When spawning one tab from another, IE gives the tabs an identical color so you know they are related; with Chrome, they are all the same color.
* In Chrome, the tabs take over the title bar, so on a multi-monitor setup, trying to click the title bar to return focus to the browser is likely to switch tabs or worse, close one. In IE, there's still a full sized title bar. My preferences would be for the tabs to leave about 10 - 15 px. at the to provide some "meat" to select the window.
* In Chrome, no matter how small the tab, the "X" to close the tab is aways available. In IE, once tabs get below a certain size, only the "X" on the active tab is active, so you can't accidentally close a tab while trying to select it.
* In IE, closing a tab activates the previous tab in the "group" (letting you basically work backwards up the tab tree structure), in Chrome, it activates the next tab, which will take you out of the "group" (which Chrome doesn't recognize anyways) if you were on the last tab of the "group".
As you can see, these are all really minor gripes, but for someone like my who typically runs 20 - 50 tabs, because I'm got 5+ research projects occurring at once, it's a big deal overall.
Keep Up with TechRepublic