I finally decided on ordering an XTB to see if it can help with some X10 signal issues in our home. The family room, over time, has moved slowly off the X10 grid for some reason. Even after unplugging a bunch of things, I wasn't able to find anything causing the noise. I've moved some stuff over to UPB, but to me, the cost of UPB (outside of Fry's clearanced modules) is too much to replace all our X10. I don't think I need the XTB-IIR, as I have really good X10 performance everywhere else. Hopefully, the XTB will co-exist with UPB. We'll find out in a few days.