You are right. I read on some forums that Guido himself confirmed that the new VST version is the same engine used in the Mojo and probably the Gemini module as you said.
I am not sure if I like the built-in Leslie effects in the new version better than the old version. Then again I didn't tweak anything. Still, right out of the box I like the sounds and GUI of the discontinued B4 II by NI. Probably more so than the piano, the tone-wheel organ combined with the factor of Leslie effects can be very very complex to reproduce.
The strong point of the gemini is that it has 11 dsp effects for each of its 2 sounds... all in a long string...
I really love the leslie, i dont think there are many that reproduce this effects much better
What i do love is using a little overdrive in the amp effect, to give the B3 sound some growl.. and then a tiny little stereo delay...and you are all set..