I have one, but it’s been in the parts-bin for over a year. I bought a GD because the XLC convinced me droppers are the future, just not an XLC one. It would sink into its travel from fully extended, only about 20mm, but that was every ride and to fix it required stripping it, which I just got tired of. Mine is one of the first though, so they might already be better.
With that said, I’m pretty sure I know what was wrong and how to fix it now, but haven’t had the time or inclination try it yet (I had one warranty replacement from B-C, who were excellent btw, but that also developed the same problem after a few months).