Misunderstood more than mislead
All of Web Designer 5 features are in Xtreme 5 and Xtreme Pro5 which was released shortly after WD5.
None of the new Web Designer 6 features are in Xtreme 5.

All features of Web Designer 6 will be in Xara Xtreme PRO 6
While Xara Xtreme 6 will still have all of Web Designer 5 features but no WD6 features.

Xtreme 6 has yet to be released. No known date for this, but I doubt we will be waiting too much longer.

What's new in Web Designer 6?
Please see here:

► http://www.xara.com/uk/products/webdesigner/whatsnew/