I've been working full time on my own business for just over a year so don't have the funds available yet to purchase a subscription. However I can see myself subscribing in the near future.
So my input is purely somebody who visits most days to read 2-3 of the more interesting threads to keep on top of the latest news.
Regarding the design I feel it only needs tweaking with things like padding, font choice, and a few colour changes. I also don't like the WW logo, to me it looks cheap like the programmer made it.
Keep the tables, keep the interface and don't add lots of features which bloat the system down. All it needs is to be tidied around the edges a little so that it looks more professional.
Remember this is a communication tool for webmasters, it is not a technical or visual guide of how things should be done the 'right way'.
Regarding the advertising. Only show ads to non-subscribers. I will not subscribe if I have to pay money to view ads. If you open threads up for public posting you will be flooded with requests of "Tell me what I should press to get to number 1 in google?!"
Personally I wouldn't show ads at all because I doubt it would be worth it due to the user type not being likely to click.
That's my 2cents.