I had thought about grinding off the bottom skirt of the L0D CE where the split ring goes. This would obviously mess up the HA but would bring it down to about the same length as the Arc AAA. I don't foresee usng the split ring and the notch in that end is kinda sharp and adds unnecessary length.
As for the Millermods Arc AAA, I think the 3/4 watt P3 versions are about the same brightness as the L0D CE on high if running tha same batteries. The higher bins and/or drive currents of Millermods would assumedly be brighter than the L0D CE on standard batteries. I don't know that any of the Millermods, even the 1.5 watt with not-yet-available Q3 bin would match the L0D CE on 10440, though.