I'm a 20yr LEO & firearms instructor. We've done several classes on defensive tactics (grappling, knife defense, weapon retention, etc.) and while LEO's carry just about everything under the sun, several things (some of which you hit on) are good to remember:
1.) decent sized blade for defensive purposes
2.) Light weight - It seems over the years that agencies have come to the conclusion we are pack mules and continue to come up with more #### to put on our belts. Any weight saving measures one can make, even in the ounces, makes a big difference in being able to chase, fight, be comfortable and long term back issues.
3.) Don't limit yourself to just one - I carry two; one for last ditch defensive purposes and one for ED tasks. Sometimes I even carry three
4.) try an get used to carrying on your non gun side pocket OR if your dept. has cargo pants, the "pen" or "knife" pocket.
5.) Practice getting to an deploying your knife one handed from different positions. This will tell you where best to carry it AND more importantly develop muscle memory which is critical in a LOD situation.
There are other things to consider and the price (like you said) depends on how much you are willing to loose while chasing folks or wrestling with a drunk.
These are my two most often carried on duty. The Endura goes in my cargo knife pocket and the dragonfly clips into my shirt pocket.
Endura Review here with some of the points I (and you) made
Dragonfly review here
All this being said, I do rotate out my main defensive knives every so often to try something new and I LOVE to carry my hinderer
JP
