I now weigh on both the counterbalance scale and the flat scale every three days. They diverge by roughly (today exactly) five pounds with the flat scale being five to the good. I started charting the lighter weight even though I was recording both the weights in my Day-Timer™. This is not exactly being self honest so I added new columns and am charting both.
My guess is that as I back down from the tropospheric weights the two measures will converge to a point where the flat scale will register within a pound, roughly, of the counterbalance scale. At that point, I may sell the counterbalance scale and just keep the smaller, more easily stored scale. But that day's a long way away.
The good news is that on the counterbalance I am half a pound away from my monthly goal already. If I could knock off half again as much by month's end, I'd be pleased. It could be considered a jump on next (short) month but I'm going to try for my monthly goal whatever the loss in the prior month was.