The drawback to the 5dmkII and other DSLR's with movie mode is that there is no autofocus while in video mode (the autofocus sensor is under the top layer of the mirror...when it flops up to expose the sensor...no more AF) And since all you're looking at is a screen where MF accuracy is highly questionable...the rangefinder system would outperform any DSLR with video mode by leaps and bounds.
But yes, serious photographers are looking more to still cameras that offer video for various reasons. I teach at a photography school, and in the PJ class they're required to utilize these functions and create multimedia presentations.