Not much of a "long" long term report, but I've had my smaller S2 for some time now. I always thought the big one was way too big for me anyways, but this one is just right.
Mine has primarily seen duty as an in pocket knife, with the clip removed, as I don't like clips on smaller knives. Plus, the S2 is so light and thin, it's best to just drop it in my pants pocket anyway, as a knife clipped to my pants would be no-no where I work. When I first got it, I used it constantly- mail, boxes, cord, nylon cable straps (small ones), fruit, and various plastic bags that defied being torn open by hand. In fact, I used it pretty hard, but then I just let the blade get really dull and put it away. Then it was on to something else!
Mine's a plain edged 7501 FWIW, and now that I look at it again, I guess it is a pretty nice smaller knife. Ti and AS-34 are always welcome, IMHO. The quality is there, nothing stands out as being an obvious omission or oversight, and it seems to perform just fine. Mine has a really crisp detent upon closing the the blade, which I've always been partial to. The blade action is plenty smooth, and feels rock-solid, with no discernable play. The lock up is strong, although I've never cared for CRKT design of the locking bar. (guess the handle shape has a lot to do with it though...)
I'm happy with mine, it's not the centerpiece of my collection, but if you can score a good deal on one, I'd say go for it.