yup. First to figure out how to load it. Then figure out how to get the rope to feed. I have tried 2 ropes, both 9.8 and both are impossible to feed.
I'm guessing a nice 9.4 rope will be fine but I'm not going to spend $300 to test that theory.
Oh yeah, the other thing I noticed about the MJ is that it kinks the rope as I lower a climber. Even if I keep it very straight as it goes through the tube. I'm not sure if a skinnier rope will fix that or not.
I have a 9.8 rope and I have not had these problems. You load it with your binner on the other side in guide mode. It is not like an ATC guide were the binner is inside the cable in all modes. I hope this helps.