Something that would plug into whatever board was available would be ideal.
Re: GSI. I do dig many of the sounds, but my DMC122 with built in Gemini, was not always reliable for me years ago. Sold it. Perhaps the module performs better standalone? I would actually would be using my legend solo for organ (always found vb3 really screechy in the upper octave, even for rock and never loved the leslie sim).
On the ipad, I've tinkered with korg module. Is that the best available? Are there other really easy to use apps with presets that don't need much tweaking?