AFAIK Wix is SEO friedly,

I don't have any first hand experience with it but I think they have an HTML Filter to help with SEO

"Wix sites are built using Flash. Although search engine robots cannot index Flash content, Wix developed a solution. As a user builds his or her Wix site, xml files are generated translate the site’s text and content into pure HTML"

look at the following thread: http://www.google.com/support/forum/p/Webmasters/thread?tid=6e1a376d2d64f5c3&hl=en

Asaf.