At least for the whack test I'd expect a knife with the steel insert to do worse, not better. I don't know if it's because the titanium galls on steel and is more sticky as a result, but where I've seen lock bar slip issues in my knives when messing around with them it's been more frequent on knives with inserts than not. Of course for wear, I assume the steel insert lockups would be superior (though is lockbar wear a real issue for anyone in practice?).
This is exactly my point.
Metal moves readily when given quick, powerful blows, or when a more massive amount of force is applied over a wider area of metal. Think of how we forge steel into knives with hammers, or that steel presses use many tonnes of force to shape metal. Heat convinces the process to happen faster but that's beside the fact.
Titanium will abrade steel, especially when you're concentrating your area of impact, such as with spine whack tests or weight holding tests.
Given that framelock knives have specific, small areas which are in contact, knowing that the lock itself is designed to *slip* in and out of position, and relies on using friction to hold the lock in place, we shouldn't assume that the lock will hold when a sudden burst of energy is applied to a small area, or a large force is applied to the overall mechanism.
Try holding 45 lbs in one hand!
I believe you'll find that in real day to day use, you'd likely drop your knife if 45 lbs of pressure was suddenly applied to the spine of the blade, rather than have your fingers bit by the edge.
I also think that if you found 45lbs of pressure gradually pressing down on your knife, you'd do something to correct the situation before you got hurt, such as moving the knife away from the applied force, or letting go of the handle.
Of course, accidents happen.
Contrast the triad lock, which uses a spring to lower the lock bar into position. This lock bar does not rely on friction to hold it in place, and in fact resists movements made in the opposite direction, whereas frame and liner locks move sideways to allow blade movement. I think this is the largest reason for the difference in strength.
Edited to add that seel-on-steel will indeed produce less wear, which means that if lockup is solid, it is less likely to fail compared to steel-on-titanium, which due to material difference, will change lockup, possibly introducing slipping.
