The free Tascam/TEAC editor was an interesting case. I wish they'd done more to support it. Last year they told me they didn't even keep a record of who wrote it.Weiss Saracon was good, and I use the Tascam Hi-Res editor almost weekly.
One of the reasons I'm interested in this subject is because of nasty DSD track transitions in certain player+DAC combinations. One solution is DSD track concatenation, which this editor provides, if you don't run into a file size limitation. And btw, I recently saw sacd_extract (SACD ripping) provides this as one option to address popping between DSD tracks.