Thanks Corey. I was going to page you for clarification on the matter. Another amp that is somewhat similar but very different is the Ampeg V2. Much more conventional in the ohm settings and a bit more grit.
The V2/VT40 shares a lot with the B15S, same basic power amp design but the preamp on the B15S is a littler different and noticeably lacks the active mid range circuit.
The V3 was just a rebranded B25 (little difference from the B25B as far as I know).