The problem with HD only is that eventually both Dish and DIRECTV will catch up in HDTV if they see VOOM working at all.
By the end of January (Feb/Mar probably for DIRECTV because of D-7s launch) I see both Dish and Direct having 10 HDTV channels, and probably by the end of 2004 15+ channels.
Given the very limited transponder space of VOOM, it will be hard for them to add a lot more HDTV channels, they need more satellites/transponders.
VOOM has 11 transponders + 2 on loan, or 13. Dish has 50 CONUS, 49 Wing, 64 Ku-FSS (equivalent 24FSS=32DBS). Dish has the same 8PSK technology. MPEG-4 upgrade on VOOM will probably net them some capacity, especially on the 10 preencoded movie channels, it is doubtful on live content.
VOOM has to offer SD channels to compete, the HD alone will not be enough, E*/D* will make sure that they stay competitive in HDTV, that combined with all the most watched cable and LIL will make customers go with E*/D* over HD only VOOM.