I think running an OS + kernel like Linux on a microcontroller is missing the point. Layers of abstraction provide tangible benefit on large complex systems but the overhead is excessive for a microcontroller. I understand the thrill of the challenge but doubt it has significant benefit.
The board looks interesting due to its audio i/o but as you point out, there is no guarantee this will survive. Also I am wary of the audio performance with so much HF activity so close to the audio. It would be good to see some data on audio performance.