I strictly used the slide release on my Sig for years and years. After all, wasn't that what it was there for?
Never had a problem and still don't to this day with the weapon. It never failed and it never failed to load a round from a mag.
Then I started spending some time with my gunsmith and he showed me the differences on the inner workings and why it is better, overall, for the weapon and the reliability for you to pull the slide back and release it.
There is nothing "wrong" with using the slide release, it isn't going to break your weapon. However the slide "pinch and pull" is a better overall option UNLESS you are in the middle of a gunfight, reloading an empty weapon & you need to get it back smoking in a hurry.
You should be familiar with both options, IMO, as you just never know what conditions you could
find yourself in under duress and possibility injured.
Take a look at the guys that preach you being able to rack your slide on your belt, beltloop or even the heel of your boot if you are injured. You just never know. Even with a shot in the hand, you can probably reload and hit the slide release easily enough.
Know your weapon, but don't just practice one way of going about things, because your world can change in a New York Minute....