Also, has no gain switch as it isn't needed. I will let Ray talk more about that at CanJam though.
It is indeed smaller than the P-51. That is USB charging on the back.
The input is on the back and the output on the front. I will let Ray tell you why there as well.
The volume controller is a double sided switch, but it still feels nice as it is spring loaded and gives you a bit of satifying resistance. I still prefer the feel of a Potentiometer, but hey that requires the use of a pic or atmel.
I imagine that the enclosure will make sure that it cannot be accientally moved to one side.