also, looking at this line on their webpage:
"Build fast with Node.js/io.js, then optimize the hardware and build thousands."
this seems like they have some right on their design preventing you from using it in commercial products.
it seems that the tessel is open source, but the pcb design is far too complicated for news ones, so i'd go for a onion omega, with the addition of a custom base board :)
and i like the appstore on the omega as well :)