Hi erasmuse, the Fallible Ideas mailing list (http://fallibleideas.com/discussion) would be a more fruitful place to discuss your ideas. There, openness to new ideas is valued, as is being willing to discuss disagreements persistently until resolution.
I doubt it. New ideas develop slowly and can't be communicated or explained until they are ready. If you look at creative intellectuals they work alone or, rarely, in pairs. Discussion to the point of resolution would be more like politics or opinion-leading; perhaps necessary for defence or for sorting out existing ideas but otherwise harmful to progress.
Work has multiple parts. Some work is done alone, some in pairs, and some in a public group. The public group part has value and importance: for example, getting more variety of criticism and other feedback such as what people don't understand. Work done in a public group also helps others learn, so that's good.
If, hypothetically, you should join the group, in what way could you find that out? What would change your mind?
Something like historical examples of fundamental breakthroughs in science or great works of art produced by committee.
Criticism is for stuff one doesn't like, which is why it belongs firmly in the public realm of news, politics, etc. A group isn't public. When it comes to your private work, ignore criticism and trust your intuition. Ideas need room to grow just like children do.