Different aspects of the KJ-45 self centering knife jig fall into different categories for me. The main event, self centering falls into immediately useful, although not in a way one might expect. My thickest knife is my Mora Garberg, with a thickness of 3.2mm. I have several Mora knives, none of which I need. I have reached the age where bushcrafting is only a mental interest. I just like Mora knives. Looking ahead, if I ever need to sharpen my Garberg, it will be far less frequently than I sharpen my several thin paring knives. It is my thin paring knives which seem candidates for self centering. If I am being honest with myself, workarounds for my thin knives do not seem difficult.
While the inner stop of the KJ-45 might seem a possible substitute for the US-430, the ideal US-430 is the US-430.If I did not already have one, for knife blades longer than eight inches and cleavers, the genuine US-430 would be high on my wish list.
I am glad to own a jig which can handle convexing, although I doubt I will ever convex an edge. None of my Moras seem heavy enough, nor are my future plans demanding enough to warrant convexing.
These are all just personal thoughts. If I was a serious knife collector or an active bushcrafter, I would feel differently. I welcome other points of view.