If both airplanes paid the same and at the 747 rate, would pay banding be bad then?
No, that would not be a bad thing. That is not what will happen though. The 767 pilots will receive a windfall at the expense of 747 pilot pay to facilitate a better ISL for the CAL pilots, thus screwing the UAL 747 pilots again.
Luckily, with the mood of the UAL pilots at this point, it is likely that a JCBA that includes pay banding will be voted down by the UAL side.