I've had SEVEN strider folders with the old lockup... never had a problem. HOWEVER, I did feel like they were on their way to "lock rock." I did have one that I took apart and bent the lockbar in to keep her tight. Understanding the physics behind new vs. old is pretty simple... there's TONS of info about it on the interwebs... check out YouTube. The old style should theoretically be more fail safe from a failure=closing on your fingers standpoint. The new style should be less prone to lock rock. Strider folders are a different animal than others. The other Midtech companies have tighter tolerances for sure. The Striders seem mo' bettah from a functional standpoint though. The tough standing ground is that most (like me) folks willing to shell out $400+ for a knife are a bit snobbish. Thing is I dont think that Striders are really that comparable to, say, CRK, HTM (Darrel Ralph), Hinderer, Shirogorov, ect... Those knives are pretty comparable to eachother, but Strider is in their own league. The BUMMER (for a seller) is that a Strider with lock rock will sell for at least $100 than NIB with no lock rock. What's AWESOME is that a buyer should be able to get a GREAT knife with lock rock THAT DOES NOT EFFECT ITS STABILITY for a steal!