Audio still loses sync for me. Happening on all sources actually if I let them play longer than 5 minutes. Audio is playing faster than the video. I think that is a separate issue though and not related to ffdshow. Possibly the renderer, maybe this is the reason for the glitches in WinDVD?
As for bitstreaming, both DTS-HD and TrueHD work great with the DSound renderer. Even 96/24 5.1 TrueHD.
@albain: