I know a bug was fixed during one of my cave/explorers ( don't remember which one ). He could shadowstride and improve at shadowstride while outside of caves, but could not inside caves. Something like that. Was fixed pretty quickly. The bug was bad enough that I thought for a long time shadowstride simply didn't work, was really bad, or was broken.
After it was fixed I had Welvinyon. He was shadowstriding all over the place vs. communes. I don't log though, so hard to say exactly how great it was. Just know it saved my bacon a lot.
Now that could be the bug fix, could be he was my highest dex cave/explorer, could be inherent sneak, could be tons of things I don't even know.
Sportsmanship killed CF