Wow, 4 pages and still going ...
If you are concerned about slide lock/release wearing, attend a USPSA/IDPA match. Just about all the match shooters will use the slide lock/release to send the slide forward and no one will say anything about slide lock/release wear. We do this primarily for speed. Using the slide lock/release with your shooting hand while the non-shooting hand is used to insert the magazine will dramatically cut time for your reload. Releasing the slide (sling shot method) with your non-shooting hand will add another step meaning adding more time.
In reality shooting situations, this extra time may mean the difference between life or death. We'll fight like we train. I use tactical techniques that will save as much time as possible to allow me as much advantage as I possible can get. And practice the time saving techniques such as slide release over and over until it becomes second nature to me. I teach new shooters to carry around their new pistols wherever they go in the house to practice drawing from holster, proper grip/aim, magazine changes, and slide lock/release until they master them. Best time spent watching TV is to change magazine and work the pistol controls until you can master them WITHOUT looking as you probably need to reach for your pistol in the dark if an intrusion takes place in the middle of the night. Turning on the light will only pinpoint your pupils and decrease your ability to see in the dark. My wife and I practice reaching for our pistols in total darkness and practice all pistol functions while we are on the move putting on our tactical vest.
I have used the slide lock/release on various pistols I have owned and performed slide release on my two match G22's countless times over the past 15 years of match shooting and they still work very well in keeping the slide locked. If there was a concern over wear, it should have been evident after 300,000+ rounds of match shooting.
To be honest, I think the notion of racking the slide to chamber a round from the magazine came to being because many shooters had difficulty releasing the slide with the slide lock/release. If it was easier to release the slide by pulling back on the slide, then this practice would propagate.
I for one have new shooters master the technique of releasing the slide with the slide lock/release (even for hard slide lock/release on new Glocks). Newer pistol models have improved, more ergonomic slide lock/releases (like M&P pistols) and using the slide lock/release is less of an issue for these pistols.