Upload & Sell: Off
I rented a 100-400 for a test weekend at Daytona to see how it did, and even with the 1.4x I was pretty blown away at both the quality of the photos and the AF accuracy. Anything above 225mm or so and it'd jump to f/8, so center focus point only, but the pictures really surprised me. I don't think it missed focus once all weekend. Pretty shocking considering. And most of these are crops from the original.
Even panning through a fence!