I haven't used the Plane Geometry spreadsheet.  And while I only fly sport models and never built a big pattern ship I know that to achieve a nice neutal handling model I've always ended up with the CG back around 30 to 35%.  And on the flat foamie I've got the balance is back around 40%.  If it were any farther ahead on any of those the models would be nose heavy and need lots of up trim.  But it would seem that Dick, our resident pattern model designing guru, agrees with your numbers.  So all I can do is shake my head in confusion and realise that I still have much to learn.