I'm for the Fox. I believe you can have the CSM 21 in a titanium frame (more money) that would bring it down to the weight of the Fox, but even in titanium the 21 is just not as appealing to me. I also have no fondness or inclination to use a 16g, since I only hunt upland (phez and smaller). A 16's a bigger bore than I want regardless of gun weight. If I had to have a 2 bbl CSM Fox set, it'd be 20/28g so my quail weren't overgunned.