How good is the IE8 browser mode in Internet Explorer 10?

Question

I've started a new project that has to support Internet Explorer 8 and above. On my development machine I have IE 10. If I open the IE 10 developer tools (by pressing F12), I can change the mode to "IE 8", presumably emulating IE 8.

My question is: How good is that emulation? I see that Microsoft is kind enough to provide us with a virtual machine running IE 8 for testing, but it would certainly be more convenient if I could do the bulk of my testing using IE 10 in IE 8 compatibility mode.

Has anyone run into web sites that are rendered differently in actual IE 8 than they are in IE 10 in IE 8 mode? It would be very handy for me to see specific examples.

Answer 1

Having done a lot of compatibility testing for front ends of major websites, I can say it is no way a full substitute for using the actual browser version you want to test in. Whilst it's useful for seeing any immediate issues, we often found that those who relied on the dev tools in IE9 onwards were missing issues which were obvious in the full versions of IE7 and IE8.