Yes Jim agreed, precisely as you described and as that foot print expands forward when digging in the aircraft will become more directionally unstable just exactly like it will with a wheeled taildrager when the footprint is to far forward. So except for that one small point I agree to disagree and like you I am not speculating causually but from experiance with a lot of aircraft over the years both my own and observation of others. The most consistantly successful conversions of my own and others is with the step at or just slightly behind the CG.

John