In the increasingly draconian fashion of our federal government "By 2007-03-01 all televisions regardless of screen size, and all interface devices which include a tuner (VCR, DVD player/recorder, DVR) must include a built-in ATSC DTV tuner."
This means that all the newest 2007 model DVD recorders sold in the US will most likely receive/record 480p/i DTV and probably also downconvert the 1080i/720p to 480i (for a standard DVD). They may also convert to Mpeg4 HD (for a nonstandard Mpeg4 HD DVD i.e divx HD, WMV HD, Xvid HD). 71 minutes of WMV HD 720p will fit on a standard single-layer consumer DVD-R disk.
Recording the 480p/i ATSC DTV signal directly will give an improvement in picture quality over encoding mpeg2 from an analog signal. You should get image quality more like DVD. You could also make a disk with 480p mpeg 2 video on it. Standard DVD is 480i and must be progressively scanned by a DVD player or tv to create 480p. Leaving the 480p Mpeg2 stream alone could potentially produce a slight improvement over standard DVD.