The cable was designed for the Harley Headset; it's possible the IMC has different impedance. Just a thought since I don’t have an IMC to test this.
I started working on a new design a few weeks ago when this all came about just in case. It is also a hand’s free, no switch design and I have so far perfected the idea. I still have to make up a prototype and test it on the bike at highway speeds.
It looks promising at the moment as pre-trials with the engine running was good. The speech quality is very good according to the people I called. I still have a few more details to figure out.
The only draw-back I see now is that you have to give up the coiled headset cable for a straight cord. I'm still looking into this but it would be costly to rectify.