I had the occasion to see the pinan katas of this style and also the bassai dai/sho (Kuda Sensei lineage).

While the kobayashi ryu in the pinans use neko ashi, the matsmura seito use a narrow stance similar to zenkutsu dachi)
The passai katas are completely different from kobayashi

Questions or the may experts of this forum especially for Dr. K:

why this difference
which is the version that is older
did Soken sensei teach pinans with this difference

thanks very much