IVTC I understand can make crap of 24fps video while fixing the 30fps. (I'm actually a bit fuzzy on the proper handling of hybrid video).
Currently I'm seeing what kind of mess MVW makes doing 100% recode to 23.976. (Which stinks since MVW doesn't know the difference between true 30fps video and 24fps with pulldown flags).
This will be used for the Xvid only since hybrid video is invisible to DVD players. Cross your fingers, this has been a rough last few days.