I have the Scientific Atlanta 8300HD box. Dual tuners and dual HD recording. It works great. The earlier SA8000HD was clunky, slow, and LOUD, and was painful for a first-gen box. The 8300 has one-touch recording, 160gig, faster guide, and very easy series recording and hard drive content management. It has HDMI-out, USB, 1394, but they have not activated the 1394 ports yet.
Time Warner does not have the 'assignable' DVR's available yet where you can send content on the DVR's hard drive to any other cable box in the house, in HD (does anyone have this yet?). They are telling my 1Q 2006 for those boxes. Currently I can send video from the DVR to the other TV's but not in HD
The HD DVR on TW Cable is $6.95/month. Pretty good deal IMO. But I still hate cable companies.