Since you asked...
Two reasons:
1) Precedent (as mentioned in my post above).
2) When I upgraded to the VIP622 during DishMover (from Maine to Texas) the equipment they installed was a Dish500 for 110/119 and a Dish300 that feeds into the Dish500 LNB for 61.5. I asked about equipment to receive 129 for the HD. The installer stated that since I had SkyAngel on 61.5 and the HD channels are mirrored I would not need 129. Now, I know this was primarily a move to contain the cost on my VIP622/DishMover installation, however I am now a subscriber in the FoxSW area who is unable to receive the HD RSN due to an installation decision that I had no part of.
Now, truthfully, I am not upset about the RSNs not being mirrored as I watch that channel very little. Based on the precedent of mirroring, I posed what I believe to be a legitimate question. If E* should start pulling HD off of 61.5, then I will be on the phone with them to push for a 1000 dish with the appropriate switch (at that time) for 4 orbital locations.
Cheers,
Red
EDIT: Looks like others have a similar problem
http://www.satelliteguys.us/showthread.php?p=861828