Full palm grip on the slide = gross motor movement, generally more reliable than pinch grip from the back which is a fine motor movement. The palm grip is also not dependent on having pinch strength and remains reliable when your hands are wet, numb from cold, or covered by gloves (not all of which have good friction). Furthermore, racking with a full palm grip close to your body is easy to do in most situations and body positions - crouching close to cover, lying on the ground, etc. - and having the gun close means it's much harder to grab, slap or turn away. Clearing many malfunctions fast (or at all) also requires palm gripping because pinch grip doesn't allow the use of that much strength.Huh? How is it more tactically sound? I mean, first off, you start with a round chambered condition 1. Right? You then unsafe the gun and fire until empty. If the gun fails to return to battery, you clear the gun and rack the slide. Your hand has no business being up by the muzzle. When you insert a new mag, you either pull back on the slide from the back, or hit the slide release.
I might ask, when is pinch grip ever the better choice? Unless you are in competition and are finding that it gains you a fraction of a second, or something.