Thanx a lot for the info, Owen.
I was pleased to read that you shoot with this amazing camera (the D300s is just great, isn't it?).
Because I bought my (same as yours) Nikon recently, I kind of found myself being under the dilemma of what ultrawide lens should I buy, to make it pair with my Nikon AF-S DX 18-200mm F3.5-5.6G ED VR II.
But, although the 10.5 fisheye seemed to me at first as a quite tempting hit, I finally purchased the more "realistic" Sigma 8-16mm F4.5-5.6 DC HSM (still, the 10.5 never came out of my heart). Your photography is an existing proof of what this superb lens can do though.