Yes, that might be so.
I really like SongMaster pro. I use it a lot, it is my favourite so far (very simple).

I only did a very quick test and comparision between the stems produced by SongMaster pro and SpectraLayers pro.
They are very similar, maybe SpectraLayers is a tiny bit clearer when listening to both and comparing them, but it is very hard to tell.
The audio forms of the stems are also almost identical but they differ a bit in places. I only compared stems for drums and bass. Anyway when I dropped the 2 versions of the bass stems into EZBass Audiotracker they produced the same midi (even though the audio files have minor differences).
The thing I found attractive with SpectraLayers is that one can have it as plugin in to the DAW just to drag over the stems into the tracks. But it is not a big issue it is very easy to export the stems to files and drag them into the DAW as well.

SongMaster pro has such a clean interface and is so easy to use.