I'd be more concerned that the Sig doesn't have the near universal positive reviews that the Colt does. I don't have a Sig M400, don't know anyone who does, so obviously I have no firsthand knowledge, and take other reviews of it with a grain of salt whether it's scathing or lauditory. With that said, the Sig AR's have gotten pretty mixed reviews, and I'd be cautious and do my research on them,