Kyatric, I would if certain addons I use were compatible. For my productivity purposes, I need them. I have been testing them since 4 on another unit. Until the addons work, my main units still use 3x.
To all affected by this issue: Microsoft have a public bug-tracker which can also take bugs for Internet Explorer: http://connect.microsoft.com/directory/accepting-bugs I would encourage everyone affected to report the issue to the Internet Explorer Feedback Program. The more people who submit it the more likely it is to be fixed.
I can't reproduce it on any games in the Arcade. Does anyone have any issues playing Arcade games in IE9? I think it might be a problem specific to previewing (which is good if so, it's much less severe than not working at all).
OK, I guess an acceptable workaround for the time being is just to use another browser when previewing, and IE9 will work once you've exported, it seems.