Finally since this seems to be about options, I would add 2 pins at .1" spacing for + and - at the power connector to allow for some male pin headers to be soldered by the user instead of a barrel connector. This could be under the barrel connector or to its side somehow. If done well, the large holes for the bigger connector could be used as strain relief if soldering in wires.
I like this idea. Sparkfun already does this on their breadboard power supply. I soldered both a power jack and header pins on mine which makes it very versatile.