Good-o,
Strip board it is. :-).
FYI, my 'design target' for this is up to 10khz pulse rate from three motors simultaneiously. That'd give you 1500rpm half stepping (3000rpm full stepping) which equates to 75ipm with a 1/4x20 thread or 1.5m/m with M6/1 thread. (135ipm or 1.5m/m full stepping). That should be more than enough for simple machines, and gives loads of 'head room' for the processor to ensure things don't fall appart. :-).
There are some issues with a single processor monitoring three stepper inputs, so this type of design has an inherent flaw. Not an issue if you don't want to go screaming fast though! If you do want to go screaming fast, all that is required is a single, smaller processor per stepper motor, as per my original junk box design.
Cheers, Me.