That's right - the developer licence is the main difference. Also, no you can't edit directly in Dreamweaver. You can view content from the CMS system in Dreamweaver, allowing you to see your pages properly. However, when you want to edit the content your browser opens up and you have to use the CMS system itself.
From my personal experience of this extension (btw I'm not associated with Webassist at all), I can tell you that I had a few problems getting it to work. I did manage to get it up and running eventually, but it took several hours and a bit of guesswork.
My advice, if you don't need to do regular CMS websites, stick with individual purchases of Power CMS and factor the cost into your quotes. However, I don't think CMS Builder is a bad product. It just needs some bugs ironing out before it becomes a great product.
Hope this helps you.
