That is totally untrue.
I flew them when they were "in" and I have flown them at 6# through 8# both with and without retracts-----not a lead sled in a car load. Engines Enya 60 III, Webra Blackhead .61, Super Tiger .61 and the current (for old times sake) Saito 82--this is a very good match for the A/C.
I never even SAW a KF III that flew poorly--------you can't screw it up that badly!

One of the very few "Every man's airplane"-------because like the Taurus the men doing the winning with them were your regular fliers-----no sponsorship necessary.

I think the only thing you may have established is that you really don't know what you are talking about on this subject.
Sorry, but it is true.