Question, are the liners SS or Ti? If they're SS, that might be why the knife's heavier (Perhaps the prototype had Ti liners?).
Seems like steel is a better choice of material for a liner - at least on the locking side. In my mind, the biggest potential problem with Ti frame locks is the relative difficulty of hardening the end of the lock bar to approach the hardness of the tang.
With a frame lock, you have a lot more mass in the slabs than in the liners of a liner lock, so Ti's lesser weight becomes a bigger advantage. Ti's surface characteristics also lend themselves more to an outer slab than steel's do.
Guess what I'm saying is that the advantages of Ti as frame components seem very diminished when you start considering them as liner components, but you still have basically all of the problems (cost, workability, durability).
As a liner, steel is cheaper, much more durable at the tang interface and really not going to add that much to the overall weight of the knife.
I would personally have preferred to see the 0350 as a frame lock, but can definitely understand why they chose to develop it as a liner lock. Rather than just being a mini-0300, the 0350 starts to compete very effectively on price - which is certainly a valid design challenge.
If the pivot in this thing is as robust as expected, and the F&F is consistent with the other ZT's I've seen, it seems like a really good value, and an overall fantastic product.
I guess if a guy wanted to go wild on the pimping side, he could build a frame lock for one.