I have had the Dillon case feeder on my 550B for about 6 years, and I am very pleased with it. It allows me to concentrate on making certain every case has been charged with powder and that the bullet is carefully placed into the case mouth.
It requires a little patience, manual dexterity, and tweaking at initial installation to get the cam aligned correctly. Once that is done, it runs smoothly. The feed tube and cam mechanism create a bit of crowding around Station 1 (depriming/resizing), but this is not an insurmountable problem.
It is important NOT to overload the hopper and rotating feed plate with empty cases; set an arbitrary limit of 100 cases and everything will work smoothly.
The people who complain about these units take issue with the noise that is created by the rotating feed plate and the cases falling into the feed tube. In my opinion, the noise is not excessive by any means. When the last case falls into the feed tube, I turn off the motor that turns the feed plate.
Others complain about the crowding at Station 1; you learn to work around this. To get something this beneficial, I'm more than willing to make a few minor concessions.
Install the unit correctly and don't overload it...and it will perform dependably. Hope this helps. Best wishes.
