I teach and recommend using the slide release, because it is much faster and much more reliable under stress.
The 'fine motor skills' argument in favor of cycling the slide does not hold up. For one thing, both pressing the slide release and manipulating the slide are very much fine motor skills. Manipulating the slide, however, is a much more complicated, involved series of movements than pressing a lever.
The 'common manual of arms' theory does not hold up either. For example, if you run the slide on an M9 or a 3rd gen S&W, you are likely to set the slide-mounted safety. Some 1911-pattern guns will not drop the slide unless you press the slide lock. Besides, is having a perfectly common manual of arms for every pickup gun in the world, worth losing a full second or two on the reload?
I won't go into the myth of conditional branching, or reliability issues here, except to say that they don't hold up either.
The only reason to run the slide when reloading is if your carry gun does not have a slide latch, or if you are physically incapable of using it.
-C