Bill:
I own both a stainless steel-handled, plain-edge Police model and a plain-edge Military model, which I recently bought.
As actual utility knives, I think they are outstanding cutting machines. The Military has a larger handle but is lighter, and the Police has a blade about 1/4" longer but narrower than the Military. Also, Police has lock back, Military is a liner lock.
I'm not sure either one would be my first choice for a "defensive" knife. Although any knife could serve in such capacity, my only reservation on the Military regarding defensive use is that the liner is exposed on one side of the handle for easy unlocking, but may under stress be accidentally unlocked by grip. My SS-handled Police might be a bit slick for defensive use, but I suppose if using in slashing/pull-cuts, either model would be very effective, though I'm not an expert on knife combat.
Probably a better choice for pure defensive use would be the Gunting, the Chinook, or perhaps the new Ayoob model.
Jim