Robin2:
Ya can't winI thought the fact that the Pro Mini uses the Atmega 328 (or 168) would be simpler than the Micro which uses the 32U4. But the USB connection would win my vote.
...R
He's an irony (advantage) I found about using the Mini/Pro Mini. You have to use an external FTDI USB board for programming via a 6 pin header. The header on (many of) the FTDI boards are usually 90 degrees (parallel to the PCB). So if you use a straight header on the Mini, the programming port is now vertical. That means when the Arduino is mounted flat in the bottom of the enclosure, you don't have to leave space in the enclosure to connect the USB cable to the Arduino. I find it takes a lot more space for the cable and fingers as it does for the FTDI board.