I don't know about the secure lock-up comparison, but I think the lockback has a longer lifespan.
I have a 15 year old s/s Delica that is tight as a safe.
I really prefer liner locks when it comes to the position of the lock release as you do not need to change the knife's position in your hand. Lockbacks must be rotated 180'.
My disappointment with my Wegners is that I have numerous other liner locks that are not showing rapid movement of the locking bar
(Leopard Cub, Spydeco Toad, MOD Trident, Socom, Klotzli). I think the steel in the Wegner's locking bar is softer than the others.
Other than that, the Wegner Jr. is by far my most comfortable Spyderco.
I even used to dress out a few deer.
I guess if I focus just on the single aspect of locking integrety, the lockback provides greater confidence than the linerlock.
Bill