I'm not sure if mine is the only one with this potential issue, but I thought I'd bring it up along with some suggestions on how to remedy it:
* Use a Dremel-like tool when making the cut-out, making sure to only take off as much/deeply as needed for the connectors to poke through
* Apply hot glue or some kind of resin to shrink the opening if it's too big, preferably in a way that doesn't leave the cartridge permanently sealed (repairs, mods)
On the user side:
* Insert and glue a sufficiently thick piece of cardboard in place
(* Hot glue - be very careful due to risk of heat damage and connectors being covered)
* Always be careful
This is the only real issue I've discovered so far, apart from the FTDI chip's driver sometimes refusing to re-mount when the USB cable is inserted, which is probably unrelated to the Harmony itself. This is fixable by running "stty -F /dev/ttyUSB0 115200" for any search engines coming by here.
Edited by Tjoppen, Tue Mar 27, 2012 5:33 AM.