Hi Dominique. Apologies for the tardy reply. We've just migrated our forums, so updates should be much more prompt going forward
To answer you questions, yes - you can now use VRFX in VJS. To be clear, the 50 vocal presets in VJS are the same as VRFX, but the newer version of VRFX has editable FX. So, pluggin in the stand alone app gives you added functionality. Also, because VRFX is usable as an AU plugin(Audio Unit) you can plug it right in to GarageBand or other AU compatible apps.