Hah. Just over half of my layout clients (that I still have) use QXP. So it is something I need to keep updated. Began with version 3, skipped a couple to version 6. Skipped to version 9 and have since needed to continue updating. Most of the clients use version 9, some 10, rest are using the current version. Publishing houses, large ones, use QXP. A lot of the European clients use it as well. Most of this work is derived from sql databases. A lot of merging and or xml. Even with xml, for which support was dropped in v.10, I use v.9 as the bridge as most have updated to newer versions. Still, it's mainly merging using complex script to deal with the data via a plug-in I use.
But as this is an Xara thread...I would be remiss to not mention there are thing in the present version that would benefit XDP if implemented. Tables for one. A means of using OT Features even though not specifically implemented in the current version. Running headers, variables, master pages all come to mind.
Probably the last one, master pages, would be of the widest Xara applicability. It would benefit both print and Web users. But I would think a revamp of tables would also. Real tables, not the silly widget at present.