So much talk about HD....
... yet so little said about the quality of it.
I own the 5DII. I'm really not impressed by the 4.2.0 quality of the 1080P. Indeed the great majority of the imager is not used when recoding 24/30fps video - all those pixels can't be clocked off the imager fast enough. The camera’s 4FPS limit is a big clue!
Talking of pixels: the number of them isn’t critically important. What is indisputably crucial is the size of the imager - the bigger the better (more light, shorter exposure, less noise, shallower DOF, wider angles); the only downside is the cost (and the larger slower mirror).
The options beyond “full frame” DLSRs are sparse, so where else do you go from there?
In some ways more pixels would be nice (greater detail but only where lens diffraction and pixel density allow), but there are tradeoffs in terms of active area (the inherent gaps between pixels that waste light) and frame speed (reduced full-resolution shots per second, and poorer quality HD video), as well as pixel noise. However, the noise issue can be largely overcome (but not the gap problem) by binning pixels together during post-processing where desired, so replicating the noise performance of a low pixel count camera – the reverse can’t be applied!
To summarise the pixel count issue: right now there is no straightforward answer as there are too many tradeoffs.
Paris? She likes exposure, or to expose.....