For me in plain clothes, this is really easy to wear concealed and to get to. Lots of options for carry if your uniform includes an outer vest. I see guys with push knives/daggers/karambits sticking out of their duty belt line in uniform and it makes me cringe.
I'm in the same boat as you in regards to formal training. I know enough that folders aren't really an option at all when things go to the ground or even in a struggle standing up. There are exceptions to some patrol guys with push daggers mounted behind a 20rnd magazine, double pistol pouch, etc on their duty belt, but yeah if it's standalone and exposed it's just as easy access for them as it is a bad guy.
Besides the simplicity of the Colonel I also liked the angled geometry of the knife as the handle is just enough for me to grab, but very difficult for someone else to. This is because it's mounted IWB using a Blade-Tech soft loop versus the rigid included G-Code hook. This also means its behind my duty belt (and glove pouch) so it's further concealed from anyone but me. In addition I wear an external carrier which sits just above the duty belt. But since Mr. Murphy is looking for ankle carry a push dagger might be the better way to go.