I have used both the X01DH 7sp and 10spd derailleurs. Neither would stay attached to the bike. I also tried locktite with no success. I sometimes have to tighten the derailleur after every run, then it will decide to hold for a while.
On the 10spd the b tension plate broke once.
On the 7 spd the b tension plate and circle clip (which holds it on) fell apart once.
The circle clips are a real pain to get on so fixing the broken b tension plate is not quick or easy.
The other problem is that the b tension screws back off over time. If they are not adjusted far enough in then (I assume because of the X-Horizon) the deraileurs go slack and bang around.
So for $350 you need to pay very close attention to your b-tension and carry and extra b tension plate kit.
When SRAM figures this out I hope they step up and help the current X01 derailleur owners out.
For now I am waiting for Chain Rxn to get more Saint derailleurs in stock…