As a retailer, If I was in this situation place the order and when the installer shows up, if its not a 722 or 722K cancel the appointment or reschedule.
They need to have a way to specify a 722 or 722K in the system. Most customers are not educated and don't know or even care if there is a difference, but the ones who are should get what they want.
Directv has the same issue with customers who specifically want an HR24.
I don't care if the stuff is referbished or new, but the recording capacity and processer makes big difference on this stuff.
One way Dish could fix this issue is if they put the option in to purchase the sling adatptor when you do the upgrade to an HD/DVR then they have no choice but to give you a 722K