Im for the .45 over the 9mm, but capacity wise there are better options. Im for something like glock 21 sf, 13+1 capacity, also wieght should be a factor. The g21sf is around 26oz vs 38oz unloaded(not sure if the marine versions will be lighter). I know my ass would stay up at night thinking of ways to shed some wieght when I was deployed, all the the cool accesories add up when doing dismounted patrols in 120+ degree weather.