The first Watch that I received was the 42mm SS Milanese. The magnetic clasp would slide and loosen throughout the day and I found myself having to re tighten frequently. It was the worst for playing golf because it would loosen with every swing. The thinness of the mesh as compared to other traditional wristwatch mesh bracelets that I own was not as comfortable because of how the edge dug into my skin. Also I didn't find it to be as breathable as others mention.
The next Watch that I got was the 42mm SS w/ black sport band. This was super comfortable and really the best for any active use. I also got some aftermarket strap adapters and now can use any of my 22-24mm traditional watch straps and bracelets with the Watch.
So I've returned my 42mm Milanese and am keeping the 42mm BSB.