I would look at getting a unit if I could use it to open doors. Also, what about using a reed switch and cam/magnate on an axle to trigger sounds, kinda like the VL sound reefers and tankers? I would so love to add those kinda of sounds to my freight cars.
Now you're launching into computer control and more complex audio effects. In order to duplicate what the VL tankers have, you have to mix audio channels. It's certainly possible, but not nearly as simple as triggering discrete sound clips to play. I seriously doubt I'm going to launch into that kind of development effort here. 
After getting a basic rig running, I do plan on introducing the processor to expand the capabilities, that will be the next step. I want to get some experience with the sounds and build a few cool projects first.
The opening doors is not that difficult, but it will require the addition of the processor. The model airplane servos I use are PWM controlled with one input. You can have the door move at any reasonable speed just by controlling the PWM output. Arranging it to open the door is pretty simple, and the servo has plenty of torque to do the job, if the door sticks, it's liable to pull it off the slides! 
