I remember a posting in the old arranger forum. Somebody tried out a tuned x1 expander from these branda guys, a keyboard dealer in the U.S. I think, it could have been George Kaye. He mentioned he wasn´t to convinced about the extra voices and stuff they put into the expander but had to admit nobody from branda was there to demonstrate this machine. One thing´s for sure: the expander is about 1000 Dollar more expensive than the standard X1 without HD. I talked to one of the branda guys to find out if the expander without tuning would be considerably cheaper, but the difference is only about 300 dollar. Nevertheless: The Branda boss seems to be very experienced in tuning organs etc.