TK,
First of all, kudos for providing such a detailed topic on this board. I'm a bit late to this forum and I wish I had found this before spending my money on the M3 board. Oh well.
I'm a bit newbie on this, and given that you have such remarkable experience, would you be willing to provide a guide on how to install a base ubuntu (16.04) image onto the M3? I've got as far as compiling their kernel by following this guide (https://bananapi.gitbooks.io/bpi-m3/content/howtosetupdockerenvtobuildgithubsourcecod.html), if it helps. I've also asked for help on their forum but honestly I don't think they know what they're doing.
I tried a few of the images that SinoVoip provides but they're super loaded with so much junk that who knows what other spyware they've installed, and I just don't feel safe using it.
Thanks in advance and I truly appreciate your help.