Being a lefty, I would not consider letting the slide go forward using the release.
On a 1911, it's quite a reach to hit the release using the index finger of your left hand. And your next-to-the-longest finger doesn't have near the leverage that your shorter and stronger thumb will have.
To release the slide on a pistol that only has a lever on the left side, like the 1911 or the Shield, I have to reach over the slide with my other hand, depress the lever with my fingertips and try to keep my palm out of the way when the slide slams forward.
My MP9 has an ambi lever, so does my G48. But my .45 Shield and Kimber CDP 1911 don't.
So why would I use a method of slide release on two of them, and have to use a different method with the other two ?
That's a sure recipe for disaster, not doing things the same every time.
And look how small the stop lever is on my MP9, do I want to rely on hitting that 1/4" long tab under stress, or just grab the end of the slide by those gorgeous fish scales and let go ?
I feel the same way about the ambi mag release on the MP9 and the G48.
I could reverse the mag release on the MP9 and G48 to "lefty", but since I can't reverse the mag release on the .45 Shield, I think it better to keep them the same.
I can hit that right hand mag release no problem with my shooting hand thumb.
Using the lever as a release might be fine if all your pistols had ambi levers, and all of the levers were the same size and stiffness.
Levers on the Glocks aren't much bigger either.
The lever on most 1911s are a good 4 times as long as the S&W or Glock, much easier to hit when the going gets tough.
You'd think that if that lever was meant to be used as a release and not just a stop, they would have been designed to be longer like a 1911.
You can do what you want, but I'll choose a method of closing the slide that works every time, no matter what model of pistol I pick up and no matter which hand I happen to be using.