Summary:
+ Looks and feel good, despite being all-plastic
+ Track name LCD
+ "Professional-ish" jog/shuttle control
+ Reaper overlays and integration out-of-the-box
- Jog/shuttle doesn't support jog mode in Reaper
- Master track signal LED indicators don't work in Reaper.
- Some other minor Reaper integration bugs
- Rubber rather than mechanical keys
- Requires external power supply
Overall build quality is plastic, but good. The shuttle control is as "professional-ish" as it looks on the images, which was my main decision to go for Behringer. While most buttons are typical backlit "rubber"-like, the MMC has a little sturdier plastic buttons (although not mechanical), which was another important factor. I really like the track name LCD. The button overlays comes with adhesives on the back, and there's one for Reaper, too.
Reaper Mackie integration isn't fully bug-free (as I expected), although my experience is that some of that is on Reaper-side rather than on the X-Touch:
* Selecting a track in Reaper, doesn't change the track shown on the X-Touch (although a firmware update has fixed that bug for most other DAWs but Reaper).
* The automation buttons don't work until automation mode is selected once in Reaper.
* While the signal level meter works for tracks, it doesn't work for the master channel.
* The track name LCD works, but the configurable backlight color doesn't - its always white-ish and Reaper doesn't seem to utilize both rows.
* The jog/shuttle actually doesn't support jog mode, unlike in other DAWs - only fine and coarse shuttle movements.
However, the manual documents how to control the X-Touch fader, LEDs and displays from the DAW using MIDI and SysEx, should one want to really DIY.
Unfortunately, it seems my device had a scratch on the 7-segment display. But hey, that's just cosmetics (and I cant exclude the possibility I actually caused it myself while unpacking it).