The differences between premium and lower grade Kahr barrels may be in their life span, as polygonal barrels are reputed to last longer, and in their ease of cleaning. The cleaning factor is one reason I like polygonal barrels personally. The steel is also different between the two classes of barrel and that too may extend the life.
The other difference between premium and other grades is in the steel used to make the slides. The price factor increase for premium Kahrs does have some quality reasons other than sight dovetail cuts, and an extra mag, (or two).
I imagine the accuracy is essentially the same or close enough for most users. Velocity differences are negligible.
Judging by today's left wing, looks like Senator Joe McCarthy was right after all.