I'm noticing the same issue with the Mac OS X version (DVD2ONEX).
However, what I also found is that when I did Movie-Only on the same disc image for the same movie, I got different output sizes when I used the two different compression options. ie the output at Constant was of a different physical size on disc than the output from Variable, of the same movie.
I had the same audio/subs on both so the only difference was the compression type.
What this implies is that the output for a <4.3Gb movie is altered in either Variable or Constant mode (or both), and NOT totally untouched as I first thought.
I should point out that the difference in total file size was marginal on the movies I tested (sub 1 meg), but even so...