Reporting back - I got the ODROID-C1, flashed the Ubuntu image onto my eMMC, apt-get install mono-complete, HG seems to work fine.
I do get plenty of the dreaded "Got a bad hardware address length for an AF_PACKET 16 8" error, but that sounds like a consequence of using the mono packages instead of compiling from master.
It's quite a bit snappier than my B model Pi, which would peg the CPU for a few seconds while rendering my HG dashboard. That said, the OS images are still pretty new and I had some issues there with ttys and the serial service. IMHO, if you had $35 for a Pi or ODROID-C1, I'd take the C1 all day long.
Gene, if you give me the details I'd be happy to create a tuned C1 image with mono+HG for the downloads page.
On the other matter, I went with paypal but think about posting a Bitcoin address
Merry Christmas, HGers!