Convince me to buy into 4/3

1. Sharpness depends mostly on the lens and the ISO, but also on the sensor;
With the 1,7/20, 1,8/75, 3,5/7,5 you can get the best resolution, if you use the E-M5, E-PL5 or the GH3, also with the 1,8/25 and NEX7 and 1,4/35 and xe-1 and xpro-1.

2. Resolution: see 1.

3. There are hundreds of criteria for the quality and usability of a camera.
Sigala1's suggestion is sensible, if you are only interested in resolution and nothing else. However, you have to limit yourself however in speed (I should guess: 8 frames per hour according to a youtube comparison of the Sigma and the Nikon D800).

Peter