On a related note, we sampled my C3 a couple weeks ago, and the B3 last week and this week. (Yes, I really have both. Hello, my name is Mike, and I have gear addiction.)
As many people know, except for the cabinets, they're identical organs, so in theory, they should sound the same. They don't, though, because there are small differences in years, and more importantly, the capacitors in these beasts are the old kind that lose (or gain?) their capacitance, which radically effects the sound.
The C3 has a very neutral sound, but the B3 is dark. So after we finish sampling it, we're going to re-cap it, then sample it again. It will be interesting to hear the difference.