You can't read B&N's ebooks on sony, yes. I confirmed this via the same method, and had that information about the versioning of Adobe's DRM.
You should, however, be able to read Sony's (ePub) books on the nook, or in the B&N software. Good to hear that Eye of the World is available in ePub

. I will download that one tonight and try it with B&N's software.
Also I recieved a reply from iRex, and they will support (for sure) Sony *and* B&N's DRM on the DR800SG.