It would certainly be worthwhile to run at least 1 DSLR, maybe 2, if you are going to get the C300 and another semi-pro camera. You can also throw some cheap, older HD Canon camcorders in the bag
(Canon has 45% off on clearence, refurbished consumer camcorders right now. Do a search at fatwallet.com, etc. About $150 for small HD cam.)
There is no easy way to get that beautiful large chip, cinematic "look" with a smaller chip camera. That is why the DSLR's sparked such a huge video revolution only 4+- years ago.
You might find more detailed information on a site like dvxuser.com
As far as the T4i, a few small things:
a) It will automatically restart a second, third, etc. file as the first file comes up to teh 4GB size
b) It has a two stage heat warning built in. It will show yellow when it is getting warm, then red before it shoyts down.
c) In good light, the face tracking algorithm, along with the touch screen and Servo Auto focus will do an excellent job of tracking a persons face and keeping that. This will help the T4i reach more into what was, traditionally, "camcorder" territory. How far depends on your needs and use.
If you want to see some beautiful large chip depth of field, this Nike ad is beautiful (not sure what camera, this is big, big budget stuff too, etc.):