Don't go with the 1156 platform just for turbo mode, it's not *that* much of a miracle.
What happens with a 'turbo' situation, is that if you are only using 1 of the 4 CPU cores, and temps are good, it will auto over-clock as needed straight out of the box. For games or video editing this wont be of much use since you'll be using multiple cores.
Where it's fantastic, is for mainstream users who don't overclock, who just want a bit of extra smacko for simple tasks, or a bit of boost to that single threaded application. In those situations it may out perform a 920. (But you're comparing the top-1156 with the bottom 1366 model remember).
You also have to remember that the 920 on 1366 supports triple channel memory, and the option to upgrade to the upcoming i9 hex-core CPU (so I'm told).
For outright performance I'd rather a 920, custom heatsink, and overclock it (seen lots of users running them well past 3.4Ghz).