Since I always show my math (5184 pixels / 300 dpi = 17.28" L and 3456 pixels / 300 dpi = 11.52). Basically in essence you would get as good print results printing at 150 dpi to get than upsampling and have photoshop guess at the pixel information.
Oppssss. I could be wrong. Sorry if I am. I've never been a print photo guy, but always video. When we refer to a 2K image, it means roughly 2000 pixels by 1000 pixels. So I just assumed that 12 megapixels = 12K image in video, which would be about 12000 pixels across, which = 40 inches at 300 DPI.
But like I said, I'm probably not correct.
But yeah, please split the 5D / 3D into a video DSLR and a stills DSLR. It's the best thing that could happen. Video is moving so fast these days, Canon needs a split video full frame model they can update more frequently to keep up with Sony and Panasonic who are starting to kick Canon's rear end really bad. Canon needs to act soon.