Well...
I re-authored my DVD using WaveLab 5 to include a static background .jpg and all seems well...
Which is to say that if I press play at the start of the disc, all tracks play through seamlessly. BUT if I cue up track 2, for instance, and then wind back a few seconds into the end of track one (as I initially did when checking for gaps), a short blip occurs as the track number changes.
I wonder if this is to do with some sort of cacheing of the data not happening properly when flitting between tracks.
Anyway, as long as this means that commercial DVD-As and SACDs will play seamlessly, I'm probably good to go. Will have to compare the sound quality between the Samsung and the Pioneer (when it arrives) and decide which one to keep.
Many thanks SparkE! for the very illuminating post - if there's a DVD-A sticky or FAQ anywhere on TS.com this info should probably be archived there.