EA = early access.
As to whether you should play now or in six weeks, I think it boils down to how much you enjoy re-playing content. You are going to have to re-play the first 14-20 hours of the game once the full release comes out since the saves aren't compatible. For some people, they may like that. It gives them a chance to play around with different builds and get a feel for what they might want for their first complete play through. Others would be put off with having to replay that much content within such a short period of time. There are a multiple ways to proceed in the first chapter though, so at least re-playing it can involve different approaches the second time around.
And yes, there will be significant amount of content and polish in the full release compared to what's available now.
Thank you very much for your input...yes, I think it will be better to wait. I bought the first DOS a good while before they finished working on the game (after its release), and had to start over--well, I elected to start over twice because of upgrades--actually played the game three times, IIRC...;) I think I'll wait because even when the game ships on 9/14 I'm sure there will be a significant amount of patching ahead of it. Yes, I should have figured Early Access...thanks. Seems kind of strange to allow "Early Access" to only a fraction of the game that will ship...not much "access" there, imo. Thanks again!