I’m not convinced we need a decision making platform. Up to now, discussing things directly worked well enough I think. That may keep working as long as the dimension of the community are relatively small.
My major concern is that a system like that would work poorly for technical decisions, since the level of technical knowledge in the community varies wildly and only a small group of people have a deep understanding of Gonk, Gecko and Gaia.
My other concern is that, up to now, the community is small and results can be easily manipulated. For example, if I had a group of friends of mine (otherwise uninterested in B2G) backing me, I would have disproportionated influence.
On the other hand, this kind of proposal has been made many times already, which could mean people feel they have little control over the project. This is an issue which must be faced, and I have no good alternative proposals at the moment.