If I recall correctly from Circuit City and here, XR boxes are similar to SA-HE-100, 200, 75, 70 (same IR codes, slight feature differences, mine is 100). In response to an earlier post, they do have 6.1 sound. Don't know about 7.1.
XRs are all digital. The disadvantage might be slight sound degradation, or so say various people.
The main disadvantage of the XR line is that unlike SA-HEs, you can no longer make toast over them nor heat your house
