The liner locking 111 mm knives have been through at least three very easy to observe cycles of adjustments. The first generation was always double sided, if there was no screwdriver to lock, the liner still stuck out from the scales. Second generation simply enlarged the protruding parts, probably to make the easier to operate in the cold or with gloves. Now, with the demise of the slider lock, we have liner locks which support single layer knives/non-locking tools in the opener layer (only protruding at the blade end if there is no (locking) tool at the opposite end).
I have just been examining my latest Sentinel (0.8413.3), and what an elegant knife it has become, but still no-nonsense and very affordable. I never thought I'd say this, but I think having the option of losing the screwdriver was the right thing to do. The knife becomes very thin and also easier to clean. It feels good in the hand, and in my personal preference, the 108 mm Solo has now been dethroned as preferred SAK when I just want a very lightweight knife with some length cutting edge. It isn't a tactical knife, it's just a nice, straightforward folding knife. The new knives are stronger, have scale tools, the steel liners will be sturdier and more corrosion resistant than aluminum, while the knives also retain their “SAK-ness”. Having a protruding liner with no tool to lock just felt a little sad, so fixing that really made a difference in my mind (also for the gripping comfort).
I think I really like the current crop of 111 mm knives. I will probably re-acquire quite a few models I already got to get the new liner lock version.
There are probably intermediate liner generations I have missed, please do add your two centicredits.