I'll also add that there is another very real tangible difference on the 30S that many will find useful.
Because the frame is 30SF frame, and the slide is slightly undersized, the slide stop/release extends beyond the width of the slide but does not protrude away from the frame like the competition stop/release does. So the part remains low profile and snag free for carry purposes, but is more accessible to the shooter's thumb and easier to get a hold of to operate.
Now I usually power-stroke rather than using the slide release. So that's why I call mine a slide stop. But for shooters who like to use a slide release but are frustrated by the difficulty of using the vestigial appendage most Glock's have for a slide release(hence the reason I got in the habit of sling shooting the slide), the G30S more accessible and usable slide release will be very refreshing.