Though I downloaded this program when you first posted, time has only now permitted that I explore a little. Thanks, Acorn, for bringing it to our attention! (BTW, the only Xara product I have used is XWDP v10-present, so these features were new to me … unlike for XDP users.)

My impressions:
The designs gallery has a lot of well done stuff, but I didn’t find too much of pertinence. Admittedly, I don’t do graphics design or print publication, so someone else might find them more applicable.
The bitmap tracer is cool. Not sure it I’ll use it for website design, but if the need arises, I’ll have it available.
The name gallery is an awesome idea. If something along those lines was in use in Xtreme 5 back in 2011, WHY has Xara not incorporated it in all of the current programs? However, short of opening a .web file in Xtreme 5 (which would perhaps result in chaos), I see no way of taking advantage of this feature for WDP365 projects.
Create brush is awesome as well. Since the brush style is internal to the document, it can’t be accessed directly by WDP. (In fact, the document has to be opened in Xtreme 5 for a brush style be used in another Xtreme 5 project.) I did find, however, that if you create the style in Xtreme, you can copy it and paste it in your XWDP project as XaraX Document data type, and the style will appear in the options for the Freehand & Brush tools for that project! Very useful. It will not remain as a permanent style, but it can be accessed if the document containing it is open. And of course, you can't make modifications to the brush style in WDP.
The Contour tool can create some nice graphics that can be copied over into WDP. The program remembers that they are contour, and it can manipulate the colors and line widths, just not the contour-specific tools. So if you know at least the contour aspects, you can create it in Xtreme 5 and then copy / paste it in WDP to implement a few details. Quite nice.
The Blend tool has similar restrictions. You can edit the entities in the blend, and a type of blending functions (i.e., the interim graphics are altered), but the way they do so is not identical to what happens when the Blend tool is used in Xtreme 5. Nevertheless, between the two programs, you can get some nice results.
A majority of the Live Effects are found in WDP under the Photo tool slideout, but a few that are more sophisticated are not (3d bump map, AV Bros, Redfield, Mehdi). Again, the work can be done in Xtreme 5 and copied over to a WDP project, as long as no further subsequent modifications are needed.

All in all, the “old” Xara Xtreme 5 is a great asset to have to supplement WDP for its limitations. That it’s free is as much the cake as the icing ��. Thanks again, Acorn, for the heads up to those of us who haven’t been using Xara products long enough to be familiar with it.