There are two basic aspects to a live performance
1) Amazing songs that feel powerful and present through a sound system.
2) An engaging energetic performer with loads of charisma or obvious talent that shines through their work.
You can skimp on one or overcompensate over the other but the whole of these two usually make or break any live performance. I think any successful product has to:
1. Sound amazing, or capture what sounds amazing about chipsounds
2. Inspires great artists to make great music
3. Has some sort of performance aspect that lends itself for promoting an engaging performance.
Things that look cool when people perform on them:
-Bashing a drum type thing like an ape
-Shredding a stick dynamically like its a huge musical penis at the audience
-fingering a little bowed box with sad tear inducing music
I would suggest you first capture the sounds you want the synth to produce, and then do lots of interface investigations to determine how you want your instrument to be played.