I haven't read of too many complaints with this lens. And I wouldn't worry about copy variation with it either. It's a gem of a lens.
But it and the 300mm f/4 are very good lens. So it comes down to zoom or prime.
Yes it is black , which I like. But a Nikon user thought I was using a nikon
. I had to explain I was using a Canon body and a Sigma lens. It got worse after that !
When I told him it was the Sigma 100=300mm f/4 EX, he said " It doesn't zoom ? "
"Yes, it does" I replied," it just doesn't extend "
He looked at me and then the lens and said , " That means it's a prime lens !" 
I really don't want to stand there and explain it again, So I said ,"Sure , that works for me 
I just never noticed because I usually focus manually.





