USB sockets mounted verticely are very very bad
reasoning:
pins have to be bent (dont think the PCB company will do this for us) as they are designed to be mounted horizonatlly
width between boards has to be bassed on usb socket and not on the minimum gap
it means that the board will require ektra cutting (yes you could have it at the edge but i dont see that happening)
if we use several square pads and a contact system on the PDA with pogo pins on the backpack we can reduce the cost on the PDA and mave it to the backpack (if you arent using a backpack its slightly cheaper, if you are you are no worse off)
not te mention its simpile to do, all it requires is a couple of squares of PCB lined up on the bottom board, the pogo pins make contact to this area.
it also means that we can route some of the other stuff to the IO boards (SPI perhaps or serial, AUDIO?)