It's about time Tamron and Sigma started cranking out really competitive glass. They have the larger audience, while the body vendors are gimped to only one platform. There's no reason Tamron and Sigma shouldn't beat Canikon. They have the entire interchangeable lens body owner market to target- far more customers than a single platform. Spend the R&D to make the best 35mm F1.4 and you can sell it to _every_ owner, not just Canikon, or Pentax, or Sony, etc.
Tamron with their 24-70 VC and 70-200 VC, Sigma with the 35mm and F1.8 zoom, both of them have now caught on. I've got a new 6D with a 24-105mm IS. My next two purchases will be the two Tamrons. Why? A six year warranty- 5 more years than Canon, way less $$$, equivalent (or better) optics, and VC with F2.8 on the 24-70.
Canon is totally detached from the market, delivering late and under-performing on critical core lenses. The management that approved the redundant 24-70 IS F4 should be fired.