i would think that a marine bot would be easier to code, seein how a commander ( comm would proly be the only human on the team ) can give his marines/bots build WP defend WP and weld WP
they just need the bot to listen to the different waypoints, ie select squad of bots, move to hera entrence... they go, as a group and secure the room with the waypoint in it, from there you just waypoint them to rt's and they build, anytime they have no waypoint they request orders... would seem like a cool bot to me, but of course thats if you like the comm chair as much as i do...
i'm not to keen on self thinking bots let alone real marines anyways
far as i'm concerned all they need to do is fire their weapon well but thats just about par for what i expect of all my marines human or not