I'm not seeing banding, rather I think there might be a fault in the Phototex. Dimensions are spot on, and the faults are almost an arc (lighter area 3-4mm across the width of the roll dropping to center, if that makes sense). For some reason, I've forgotten how t oupolad images here...
Images on Phototex, with a new photoblack profile are much more vibrant than 8400, but it still bruises on dense colour using the softest felt squeegies, though goes up nicely with a brayer roller (but takes 5x as long).
Only other issue I'm seeing on the 4600 is the number of head cleaning it runs - no headstrikes, but every 3-4 prints, and no sign of print deterioration prio to clean.