Would it be appropriate to ask this on the main site or should I start a chat room? If I start a chat room, how would people know that it's there?
I wouldn't bother with a specific room. As you say, nobody would know it's there. However, that's a perfectly good topic for the site's main chat room. Just drop in there and see if you can get anyone interested in discussing this.
Many (most?) of the regulars use unity and are facing the same dilemma you are. It shouldn't be too hard to get them to talk about this.