Martin - what ideas do you have in your head for Moodle 2? Are you contemplating biting the bullet and doing a complete ground-up rewrite, or is this more a case of running over the existing code making generalised improvements?
There is an old saying (which I have found to be true I'm afraid) that a software project is never right until you have completely rewritten it for the third time. I suspect you didn't know what Moodle was going to look like when you laid down the framework for the current version. Would you have done it the same way if you know then what you know now?