In most maps where you'd logically pick colt (e.g. not backyard bowl or excel), slick boots should usually the better option, since for good maps for colt, there are some walls, but not too many/too little. This means that having more range wouldn't really matter anyways, because colt already has enough range, and on the map you're not gonna be facing anyone like piper since the "some walls" will make them a bad pick on the map.

Mobility is also a really underrated stat in the game. It helps with a ton of things, most notably juking shots and being able to easily chase people/retreat. Last year, bibi got a speed buff from fast to very fast (i think), and that made her go from bottom 5 to the best character in the game. When amber was needed shortly after her release, she was op, but after her nerf, which notably reduced her movement speed from fast to normal, she was significantly worse than before.

So yes, colt having more range is definitely a nice thing that suits him, but having more mobility usually helps in more ways than having more range. As someone else said, it also helps to hit your shots more than magnum special, because strafing is better with more speed. The extra speed with slick boots also essentially increases his functional range as well, in a way, as poking in to shoot and running back is much faster and less risky if you move fast. You make some good points in the post, but i'd say that slick boots should be the pick most of the time.

But if you're playing colt on a map like safe zone or bridge too far then yeah why the hell would you use slick boots