Based on my research I had chosen the Radxa Rock 2 as the brains for the Singularity Robot (that I posted a while back). Now that I have been working with the Rock 2 for a while I've realized some harsh realities. It appears that Linux isn't fully supported on the Rock 2 setup. This includes the GPIO not working along with who knows what else. A good friend chose to go with the Odroid XU4 and he is having great luck with it. GPIO and all, sigh. This is not to say that the Rock 2 is not a great computer. So far it has been great. But the intent here is to use it to control a robot, which is not going to happen in a meaningful way unless it has a way to talk to the hardware. Now, I could use USB or some other form of PC-style communication, but the whole point of a single board computer is to use it's on-board GPIO. I can't see adding more hardware to support what the Rock 2 should support out of the box.
That said, the Odroid is on it's way to the lab for testing. My assumption is that it will do the trick. I will post my findings.
Lesson learned. Spend more time on the research phase.