(new) Lenses wishlist

Better quality at telephoto...

My wishlist for Sigma, that would get me a little closer (the SD1 price drop has me thinking about it again):

70-300 OS HSM, with better quality @ 300
400/5.6 OS HSM or 500/5.6 OS HSM or 400/4 OS HSM

and also...the 16-80 that the OP mentioned

One of the reasons I have been resistant to switching to SD1 (outside of the ridiculous initial pricing) are telephoto options (at a reasonable price).

My experience with multiple Sigma telephoto zooms is that there tends to be large fall-off in image quality at longer FL. I have owned a 70-200 (not OS), and tried 120-400, 150-500, and 50-500. The 50-500 seemed to be a little better, but was noticeably better on the shorter FL, and is moving out of my price range. I have tried the 120-300mm, and it is better, less so with a TC, but too expensive to justify.

The Sigma 70-300's seem to be pretty weak at 300, per the reviews I have read (which I am inclined to believe based on my experience with the other zooms). I would even say the entry-level Canon 55-250 is better @ 250 than any of the Sigma 70-300 offerings @ 250+. (My copy of the Canon 400/5.6 is excellent.)