ECQC is very very high on my class wish list.If you're going to do this, use a locking sheath. Every weapon on your belt is another one you have to protect from a grab attempt and officers have been stabbed with their own blade as well as shot with their own gun. When I was a field sergeant some of the young guys would do the center line knife thing without thinking that part through.
Highly highly recommend Craig Douglas' ECQC for weapon retention training. Head and shoulders above anything I've been shown anywhere else, including the Academy.