If it wasn't for IETester I had to install multiple virtual machines to test web pages for different IE versions.
It will be easier to use without these extra thumbnails.
As a personal opinion (a lazy web developer), I think it'd be even easier to use if tabs weren't reflected in taskbar thumbnails.
Because if I switch off the IETester, usually I'm going to change a piece of code in my editor and come back to see those changes in IETester. So the active tab is my main focus and extra tab thumbnails will just make me to choose the tab and click one more time to get back to IETester.
Anyways thanks again for your attention