look here
http://sourceforge.net/projects/projectchronos/?source=navbari use this Chronos2 with muy 600D and ML.
i am happy with this control. simple and this have so many cool stuff inside. I use a leadscrew.
you can use this control for beld and screw drived slides even for what ever what its driving with stepper motor !
depend on what you will make!
i think the Raspery Pi its a good solution too. i have 1 and i am experimenting with this, learning programming , only time its what i dond have so much!
i am building right now the Pano axis and vertical axis, for the movement i will use the same control system.
so i have all axis complet independent.
the think its keepit simple, in the field i dond wont carry too much stuff and i dont think its a good idea too putt the control of the slide on the cam. The Cam have to do so much another thinks.
in this way we discover the Canon Firmware its BAD! look the 30 sec time! on Canon on ML and measured! its funny
Dirk