pluggy:
The chip in my home brew is mounted on stripboard, the chip is the same one used in most Deumilanove/Uno/numerous clones. The Leonardoi is surface mount and wouldn't fit, Surface mount is tricky on a small scale hobbyist level. At a push you can program the chip on a Uno, lever it out of the socket and stick in it your own board. Its just about practicalities.....The other picture shows it mounted on what I designed it for : mounting on a Raspberry Pi. http://www.raspberrypi.org/faqs
So .. simply you say that Leonardo chip cannot be extracted out of the board and be stuck in and programmed to my board for a beginner like me. And UNO is easier in that part because I can push it out of the Arduino board socket and then put it into where board I like .. isn't it ? .. ok that's comforting because I've already ordered a leonardo !! .. but by then, how can I know the right pins of the chip and connect them to the right elements in my circuit ?
Rasberry .. I see now .. so do you recommend me to change my order and buy an UNO ?