James,
again, for what I typically shoot, it's probably not ideal. I only use a tripod in the studio occasionally and at National Specialties. Hardly ever for my nature walks simply because it's too darned clumsy to lug around. I realize that is something I really should learn to do but so far, I've done OK with my 200L and a 1.4 TC without the need for a tripod. For ring candids, the Sigma is probably longer than necessary. I can cover virtually any ring with a 70-200 zoom.

However, I can definitely see where it would be a viable choice if I were doing a lot more wildlife shooting. I used to own a Sigma 70-200 F2.8 zoom and it was super sharp and worked great with the Sigma TC. Personally, I've not had any problems with any of the Sigma lenses I've owned over the years but I do hear a lot about variability issues.

Great review.

Jim