I wouldn't call myself a collector but I have quite a few Kahrs in my collection, all 9mm and .45ACP though.
Every one has required an extended break-in of 200+ rounds to be reliable, and even then, there are types and styles of ammo that are not a good match. Particularly, all of my guns shoot better with the heaviest bullets I can find - in 9mm that is 147's, and in .45 that is 230's. With lighter bullets, I almost universally get all sorts of failures to feed and eject across the product line T, P, CM and CW included. Both my 9's and .45's also hate short OAL rounds, to the point that when I rotate my carry ammo, most brands experience a bit of setback after repeated chamberings, so I end up putting those rounds in the practice ammo bin.
You can cut a bit off of the break-in with scotchbrite if you really don't have the quantity of ammo required, use oil, and polish the metal contact areas.
Also, there is this:
As far as the variations, I note similar design differences in my 9mm Kahrs, even between different generations of the same model, produced years apart. In some cases this has lead to the need to do some extra polishing, and one factory replacement slide stop, but nothing more serious. These are not Glocks but neither are they hand-built one-offs. You should expect to see some variation, and I personally consider it normal.