I find your question interesting because it reflects, I suppose, how you will need to negotiate with each other to reach a consensus.
That said, you also have the challenge of agreeing on a specific electoral system. Based on the experiences of referenda held elsewhere, the challenge is to reach an agreement on a type of electoral reform and on whether you'll choose the mixed, proportional or preferential system.
I don't want to interfere with your negotiations and the committee work, but it seems you must reach an agreement first on the electoral system you want to put forward to the public.