I've only been flying for a few months and so don't consider myself nuanced enough to know the difference yet, but at my level, they seem very similar.

One thing about the Tai Ji is that the battery compartment is small and there's not a lot of room to move the battery around to adjust balance. People have resorted to moving the servos from the tray in the front to positions in the rear, or adding weight to the tail. That was not necessary in the Osiris. The fit and finish seem pretty good. There are some nice touches in the design. The guy at Airborne Models is helpful and responsive. Go over all the joints, especially near the LG, with glue.

There's a pretty good [link=http://www.rcgroups.com/forums/showthread.php?t=1516967]thread[/link] over on RC Groups about this plane, and some of the participants, who are more experienced than I, have had both the Osiris and the Tai Ji. Check it out.