hm, you're suggesting making one rough post in discussion, then use feedback to make a second post in main? I can see how that's often useful advise, but I think I'd prefer to try and thoroughly justify from the start so would find it hard to avoid making a Main length post straight away. Revising the post based on feedback from Discussion before moving it seems like a good idea though.
Well, you have three layers in LW: a post in an open thread, a discussion post, a main post (who might get promoted). Within these you can pretty much refine any idea you want without losing too much karma (some you will lose, mind you, it's almost unavoidable), so that you can reject it quickly or polish it until it shines duly for the main section.
Previous Open Thread
You know the drill - If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one.
3. Open Threads should start on Monday, and end on Sunday.
4. Open Threads should be posted in Discussion, and not Main.