That does seem very similar, though it looks like multiple people are having that problem with the same board, where as it seems like plenty of people are using it with the rPi no problem.
I have found a solution though, sorta.
I decided to put the card into a rPi2 and in this case it didn't start up even with the HDMI connected -- it would get stuck at the DHCP lease for some reason, even though it did acquire an address and was responding to pings.
I thought since it was responding to pings but nothing else, maybe this was the same place it was getting hung up booting headless with the rPi B+ so I put it back in there and started it up with the HDMI cable connected so that I could open the web interface. I set the IP address/subnet/gateway in here to a static address rather than using DHCP. It now boots headlessly from the rPi B+ or the rPi 2B with no problem.
So it seems that it was having problems with DHCP, but for whatever reason, on the rPi1 it didn't have a problem with the lease *BUT ONLY IF* the HDMI cable was connected.
Those things seem more or less unrelated, so I tried turning DHCP back on and confirmed that yes I had the same issue -- won't start from the rPi2 but does respond to pings. Won't start from the rPi B+ without the HDMI cable plugged in but does respond to pings. Does start from the rPi B+ with the HDMI cable plugged in. I set it back to static and it does start from both rPis regardless of the HDMI cable. Very weird, but anyway, I'm up and running.