FWIW, radeonsi can handle much more than 'some basic 3D demos' now. It runs many real games / apps fine. 3D apps run at full acceleration including page flipping. We're very close to enabling full glamor 2D acceleration as well.
Obviously it's not nearly as mature as r600g yet, but it's certainly ready for wider testing by early adopters.
I am interested in the word "we're" in your statement. What exactly is your involvement with the driver?