The fact that you shoot 75% video, I would think the new AF system in the 650D would make it worth the higher price. There are also a few more improvements
. Until there are some "real" in-depth reviews, we won't really know how well the "new" sensor performs compared to the 600D. Unless you have to purchase now, wait a bit for more accurate reviews of the camera are in, as well as more stable pricing (and possible deals). From what I've heard, the 600D isn't going to be discontinued and replaced
by the 650. It's supposedly going to be sold along side it as the 550D has been to the 600 so no rush before all the 600Ds are gone.