As far as the Its a knife I can pass down to my children so they can use it argument goes;
Does anybodys son really want the greatest folder that their Dad bought 20-50 years ago?
Heck no, except for sentimental reasons maybe.
They want a modern knife. They want the better steel, the better locking mechanism, the better materials, etc.
Knives, and everything else, evolve. Almost no product is so good at its inception that it remains essentially unchanged, and unchallenged. (OK, a 1911 is a major exception)
The idea of passing the knife down to my sons and grandsons, with the idea that it will gleefully replace their modern folder, is wishful thinking at best.
I dont think my Dads (state of the art, 1967) Case is a better knife than anything in my current collection. It may be an heirloom, but it sure isnt very good to use anymore. It has inferior blade steel, inferior F&F and inferior design. What is appealing about those traits in an EDC? I can buy a $40 Kershaw, Spyderco or Benchmade that will blow it out of the water.
Titanium framelocks are a dime a dozen now and many inexpensive ones are very good. The Sebenza isnt a unique design anymore. Its only a grail and legend to those who make it that way. Good knives, but not all that.
There have been a few folders that I regret giving away or selling. I really liked these folders, despite the brand, cachet, or cost. Most of these I have re-bought. The Sebenza and Umnumzaan are not among them simply because I didnt like them that well.