All I can say is that I'm still quite happy with my T2i so I would go for the lower end model and investing in better glass. Since this will be your first time shooting video on a DSLR as a primary activity, now is a great time to get used to the format and learn all the ins and outs. You will find for documentary and news work you will have to invest in sound gear or else the camera will be unusable for those uses. Glass is always a good investment and I would put sound in the same category. The advantages of the T4i over even the T2i are not so great that I would rush to buy the T4i, the 7D or the 5D Mark II are another matter entirely...if I could afford either I would buy them in a heartbeat.