First, to answer Jeff's questions:
No functionality should be lost, either in the main site or forums. We have contractors working to match the functionality we have now, hopefully with a few improvements, but the goal isn't to change things too much. It's to replace what's there.
There are substantial changes coming from Google (and likely Bing) that have a high preference for sites that produce a mobile version. The existing nHibernate (main site) code doesn't render well on mobile, and it's substantial work to add that. This is an older version of nHibernate, and we have limited resources internally for this technology. We've had a few outside consultants look at it, but it's a substantial project. In addition, we would still be dependent on external resources.
We do have internal WordPress resources, and have moved both Red-gate.com and Simple-talk.com to WordPress. Between styling and plugins, this has been a success. As a result, and with the recommendation of a consulting firm, we decided to move to WordPress. There will be some styling changes, but this should be minimal. In addition, with Project Nami (https://github.com/ProjectNami/projectnami), WordPress has been ported to run on SQL Server. There isn't a lot of db stuff in WordPress, so this isn't much of a concern.
There is work for plugins to get the different article types, the briefcase, the Questions of the Day, etc. moved over, and we're developing items here.
We hope to get a beta site ready in Nov and a deployment by the end of year.