But when I export to a QT (using the same HD codec) they look awful.
Have you enabled HIGH QUALITY PLAYBACK?
Shane's Stock Answer #22: Enable High Quality Playback in Quicktime
If you want your footage to playback at full quality, then you need to enable High Quality playback.
Open the file, hit APPLE-J. Click on VIDEO TRACK and then click on the VISUAL SETTINGS button. Check the box next to HIGH QUALITY on the lower right hand side and close the window. Type Apple-S to save the movie.
Without that, the computer is playing back a low res proxie.
I have never had issues of jaggieness with my titles in DVCPRO HD. Sharp as a knife.
I've burned the same QT using DVD Studio Pro to a DVD and watched it on a NTSC TV and the results are identical. Jagged, low-res titles, great image
How did you encode? Unless you did a High Quality Encode with Compressor, they won't look their best. And do know, that you are taking an HD source, compressing it to an SD MPEG-2 format that you are putting on a DVD. Titles won't be VERY sharp, but won't be jaggie...if done right. I have done this lots with great results.
Shane