Bill, actually I am really enjoying all the thought-provoking discussion here.
One thing I'm getting out of this is that there does not seem to be a clear demarcation between 'flat-top' and 'archtop'. For example, at what point (radius) does it become appropriate to call an instrument an archtop (20', 17', 15', something else)? Or, should the term archtop be reserved for carved instruments only? From a consumer standpoint I think this is an important question.