It's my opinion that the 14.5" government profile mid-length gas system would be the best of all compromises for a standard patrol carbine. The middy 16" being more practical for most. However, are you an Officer in a rural area or urban? 11.5", again in my opinion, is great for urban areas provided you are issued/allowed to use proper ammo. There are just too many variables/unknowns to say this or that is best for YOU though. Keep in mind that a man with above standard training and sub-optimal weapon will generally prevail over sub-standard training and an optimal weapon... both being mechanically sound of course.