The TV will likely eat the most power.
I would take the HR24 for the recording option but that is going to use more power than the H25 due to the hard drive. With a SWM manual portable antenna the HR24 will not need the BBC devices and only 1 coax is required to power both tuners.
I would not buy a dome since you would get NO HD and when DTV drops their SD programming no one knows which channels will be available from the 1 and only DTV satellite the domes can pick up (101).
Pick the right hardware to do the right job and figure out how to handle the power instead of the other way around.