An interesting interview with Andy McNab in the Nov. 2011 issue of the American Rifleman. He was formerly with the SAS. Says they tested both the SIG pistol and the Glock for several years and decided the best choice was the SIG. Said the No.1 consideration is that the gun go "bang" every time even after lots of time and neglect in the jungles of SE Asia.
I've always heard good things about the SIG pistols but never thought or heard they rivaled the Glocks in reliability. So this was an eye opener for me. E