I'm a recent user to Skydemon. It has worked perfectly for navigation with my old GPS receiver, an Emtac BTGPS III. No issues at all.

However, I've recently upgraded to a new receiver (here: http://www.gns-gmbh.com/index.php?id=79&L=1). It offers some benefits as it has a faster refresh, support for more constellations than just GPS, and SBAS. And also has a longer battery life.

The new receiver works flawlessly with Memory Map both on my PDA and my laptop, as well as with my Android phone. However, Skydemon will not work with it. When entering Navigation mode, it simply says "Seeking Satellites, 'n' found ('x' out there)". It never gets past that and never gets a fix, even though it often 'finds' as many as 15 or 16 satellites.

As long as your receiver outputs standard NMEA messages, there's no reason SkyDemon wouldn't work with it. Perhaps it is failing to emit the fix accuracy messages, which would cause SkyDemon to not process the data received.