I mostly use twitter to find out what people I am interested in are up to, so my usage here may be shortlived if they don't also use it. I love the federation and community moderation ideas, lack of advertising, etc., but I rarely post and want something to tell me what's going on. I really hope the developers/writers/critics/etc make the move to Mastodon. Knowing how Twitter treats app developers, I doubt there will be a lot of options for dual posting to both networks.