[Rover]

If you mean the 35/2.8, I can't imagine why anyone would bother with that, other than for the dearth of AF 35mm options in the system. If Sigma beats them to the rush and makes something similar to the (highly regarded) Voigtländer 40mm f/2 - but with AF, they're going to sell thousands of those. Or even a "regular" sized/shaped 35/2 for that matter. It's funny how densely is the 50mm(ish) focal length populated now while at 35mm the situation is... weird.

 

But back to the 6D successor...