Billing for my new Plan has now settled down.
My monthly bill was
$74+ (after the quiet $3 increase) and now it is $55+. This year I will save $228 with the new Plan. BTW, apparently, the new rate includes a $5/mo discount that will continue for a year.
I have continued my habit of monitoring and logging thruputs morning & evening and I have experienced no changes in the speed patterns since the change.