You're not the first one to mention DVD authoring over Re-encoding, but to be honest, authoring with both DVDLabPro and TMPGEnc left quite a bit to be desired. Demuxing and then remuxing led to audio sync issues and didn't improve the video quality over Recode, DVDShrink, and definitely not better than DVD Rebuilder.
The conversion program that I use to convert certain files to DVD compliant format (1ClickDVDMovie) uses the MainConcept Encoder and also encoded videos that was atleast as good as the authoring programs you refer to, AND no audio sync issues.
So while you feel thats perhaps best for you, it was nowhere near worth it to me. Certainly not DVDLabPro for $200 bucks.