Just an opinion.. Lots of people trust you lot. Next time there is a security issue and you do release 2.0.x, if there is a change/new functionality that is beta, alpha or worse then that is extremely bad for a GA product. Start the 2.1.x branch! Agree rough timescales bearing in mind you may need to do a 2.0.x release at any time. Say 2.x every 9-12 months. 2.0.x as needed but within a week or two. If something is going to take longer than a couple of weeks to get GA, then put it in 2.1.x. If that feature is needed in 2.0.x, then back port it once it is GA. Look at how they do the Linux kernel.
Sorry if this pisses people off, but it's just common sense. Dave.