I started with a GP40 myself, using it is easy something a 6year old could do so its not a bad move at all, it just cant take analog inputs.
the the LeoBodnar256A13 or B256A13 if you are going to do a whole pit it will
be cheaper and will have less USB ports and power cables used. Just be aware it doesnt have screw terminals like the GPwiz so soldering it is!
http://forums.eagle.ru/showthread.php?t=80201&highlight=leobodnar