I could be wrong, but methinks that Horizon is asleep regarding that manual. For whatever reason(s) it would appear it needs to be updated. In MinnFlyer's review (link posted above) you'll find this note as well as a couple of mentions regarding this problem:

Tech Notes from Seagull: The center of gravity noted in the manual is too far aft. The CG should be 2.75 - 3.5" (70 - 90mm) behind the leading edge of the wing.

These same dimensions are used in the manual supplied with my kit (70-90mm).

Interesting, as I didn't know what the original CG spec. was, will keep that in mind as I sort through this! Thanks, -Al