BarryHercules

Interesting review.
Mr experience of Wacom Vs XpPen was exactly the opposite.
I returned a brand new Intuos Pro after just 3 days for all the issues you ascribed to the XP - inconsistent pressure, janky lines, and woeful wireless connection.
I bought an XP pen 21" for the same money, used it for 18 months, then upgraded to the 24" at launch.

For reference, I'm a Windows user, but spen't 10 years on Mac before switching over.

Personally, I found the XP just as easy to set up as a Wacom. The driver and software is a single file - install and restart. The complex issues described here must be Mac specific.
Your issues with calibration sound unusual, especially if the settings interface is the same as Windows.
Calibration is a case of 5 clicks on screen, and setting a drop down menu to assign the active area to both screens, a single screen, or a user defined area.

In use (and I use it professionally & daily, for ZBrush sculpting and both vector and raster illustration), I find the XP to be perfectly decent. I wouldn't hesitate to purchase another one.

I know it's not a Cintiq, but is it £1100 worse than a Cintiq? Not at all.

I'm not trying to batter Wacom, or question your experience of the 24 Pro, but as a user of XP products for the last 3 years or so, I just wanted to point out that this experience is not a universal one, and might be down to issues with your specific circumstances, rather than a reflection of overall product quality.