Having said that, I designed my own site using Wix which is Flash-based and has unlimited flexibility from a design perspective. I can put anything I want, anywhere I want and style it anyhow I want.
The interesting thing is that the site I designed for a client recently who specialises in Social Networking and business was in WordPress (of course) has almost identical Google Analytics as mine. Now isn't that interesting. I am actually getting more traffic to my site because I'm using the social networking tools regularly. But the Google search engine doesn't seem to be sending any more traffic to that business than mine. Actually the opposite. So, watch this space for regular updates on that.
In the meantime, I am recommending WordPress for businesses which need traffic and Wix sites for information-based sites not reliant on search tools.