Sigma 18-250 compared to the CZ 16-80?

[Al_]

I have the CZ 16-80 that I use probably 80% of the time. I really like this lens. I also have a Tamron 18-250 that I sometimes use when I need to travel fairly light. But the focusing is slower than I like and the performance at the long end is ok but not great.

I've read Dave's article on the Sigma 18-250 and was thinking getting the Sigma to replace the Tamron. My question to anyone who has or had both the CZ and the Sigma - how is the Sigma compared to the CZ 16-80? I know I would miss the 16-17mm range, but how does the image quality and focus speed of the Sigma compare? Any thoughts are appreciated.