First, I will assume that you actually mean 60D, instead of 600D (aka Rebel T3i). This is somewhat of an apples to oranges comparison, as the 60D is a prosumer camera, while the 650D is a consumer camera (and I say that with all due respect for its capabilities). I personally have a 600D (and a 550D and a 5D Mark III). The 60D's build quality is said to be quite a bit superior to that of the 600D or 650D. The image sensor in the 60D is the same as the 600D and the image quality from the 650D appears to me (from posted video samples) to be no better than the 600D (or 60D).
Second, it appears to me that the new technologies in the 650D are the video auto focus and touch screen. If these are things that you really want, then I would say that the 650D is a step forward. I suggest searching Vimeo for some videos of the autofocus in action to make sure it works as you would need it.
For me, I don't consider the 650D a step forward. Indeed, for me it is a bit of a step backward. I say this because Canon did not put one of the 600D's key features on the 650D: 3x digital zoom. All DSLR's suffer from aliasing and moire issues. Canon almost completely eliminated it in the 5D Mark III. But, the 600D, 650D, and 60D all have it. But, with the 3x zoom feature on the 600D, you can nearly eliminate aliasing/moire. See https://vimeo.com/35111205
. Again, the 650D does not have this feature and the 60D does not have this feature either.
Worse, I've not seen any evidence that Canon has made the 650D less noisy (i.e., better in low light). Therefore, I see no new technology that really results in better video quality over the 600D (which has the same video quality as the 60D).
Finally, if you are not aware of Magic Lantern, you should look it up. It is a very useful third-party firmware that can be installed on both the 60D and 600D today. Magic Lantern has many features that are very useful for video (and many for stills, especially timelapse). It is not yet available for the 650D.
So, if you weren't already considering the 600D/T3i vs. the 650D/T4i and 60D, I suggest that you add the 600D/T3i to your list. Good luck as you do your research and decide on which of these great DSLR's work for you.