My Genie arrives on Monday (upgrade from older HR-21 DVR). Yay! I want to add a 2-3 TB drive (external). Questions: Does it affect the speed of operation of the unit (the user interface)? My HR21 is slow and I don't want to hamper the new unit's speed. Any recommendation as to disk drive? I plan to use the same e-SATA enclosure I have now.