Mixing Nikon D3S with Canon 7D?

Has anyone tried mixing the two at an event. I know the nikon shoots 720p and canon shoots 1080p. I wonder if I uprez the 720p to 1080p, if it would make eventhing looking fine… I'm doing this for a wedding shoot.

If I was shooting video (especially for a wedding), I would prefer to use a nice video camera instead of a camera designed for still photos with a video "feature".

That is the reason I have both a video camera and DSLRs… Each one has a specific purpose. But then again, the reason I bought my DSLR was that it did not do video.