I can now say I'm satisfied with the design of the case and the firmware. I pulled out all the power-saving tricks I could, and the AVR system monitor draws very little current when the device is off. I've also been tweaking and finalizing the case design. Both pieces of the two piece assembly now fit together snugly and the PCB lines up perfectly with the rear holes. All that's left to do now is to start building these things, and smoothing the cases with acetone vapor.