I haven't had any problems with my outrider, but then I only use it for outdoor recreation.
The side lock on the Outrider looks pretty positive. There is a hook on the underside of the main blade's spring. The side button is attached to a bar that crosses the frame under the main blade's spring. When the blade is open, the bar engages the hook, which prevents the spring from lifting and the blade from closing. Retracting the button disengages the bar from the spring and allows the spring to rise and the blade to close.
The lock's strength is limited by the strength of the hook, spring and locking bar. I've spine whacked mine with a screwdriver and it did not disengage, but I didn't whale on it. It's not a hard use blade.
The big question I think is relaiability. It looks like debris could easily get under the hook and prevent the locking bar from fully engaging. If enough debris got in there, you'd have a slipjoint.
P.S. As el cid points out below, some of the Vics have a liner-type lock. I don't know anything about those.