Yeah, the new version is supposed to be better. The Sigma Version is actually 2 different versions. I have the Sports version which is a beast. Yes you can get better pics with the Canon or Nikon using their 600mm but that's a dedicated 600mm and costs much more than these. I don't think you can find a better long zoom, especially in this price range. Nikon has a 200-500 that is very good too and comparable price.
I took this with my Sigma 150-600.