This is a great idea. Should definitely have a silver and a gold. There are definitely different atmospheres on each of the different sites and this would encourage people to expand their horizons (or at least the badge lovers :P ).
I think it greatly benefits everyone to spend a little time "on the other side". Even though I have less than a milliSkeet of rep on SO I've not been discouraged from watching things there and learning first hand from some the best in the industry. I started out life as a sysadmin and am relatively new to the coding side of things. I have noticed that my code quality and practices have gone up significantly in the couple of months that I've been watching SO.
The better one gets in all 3 areas that the trilogy cover, the more you'll understand how to cover those aspects and the more complete your solutions can be. Anything (within reason) that can be done to encourage that is worth considering, IMHO.