ORIGINAL: Mustang Fever
I'll tell you what, there are more CG location mistakes made in manuals and on plans than any other mistake I can think of. You'd be well advised, Pete, to learn how to determine the mean aerodynamic chord and locate the CG yourself, at between 25-30% of MAC.
In 25 yrs of RC I've never seen a kit or plan CG location that wouldn't adequately fly the aircraft. Balance where the designer or kit mfg suggests and fine tune from there. I'm totally unfamiliar with what you seem to be calling a major discrepancy with kits, plans, manuals where the CG is concerned.