Hello all, I've got to chime in here.
I gotta say the dillon 550 with NO case feeder once properly set up is IMO the best running press out there! And super fast on caliber changes even with changing primer size. However, I will say with the case feeder it's a pain in the ass. If you don't have to change the shell plate it's easy like going from 9 to 40 just swap the tool head and the adapter on the feeder tube. Literally a 2 min change. Now I've used both hornady and the rcbs and the reason I stay with dillon is because of there priming and powder drop systems. If you would blow a primer when seating it WILL NOT affect the other primers in the tube. The biggest thing is how accurate and consistent the powder drop is. It is very easy to adjust the powder charge even without the add-ons. Don't get me wrong hornady and rcbs make great presses but for me the dillon just works out better. I am a big competitive shooter as well as an instructor and ill load a few thousands rounds on one caliber until I change. The dillon is a tad touchy setting it up but once it's dialed in man it's wonderful! Just keep it clean and lubed. The only other thing I had issues with was when I first got my dillon I was using rcbs and lee dies. The flare on the bottom of the die wasn't big enough and sometimes I had to guide the case into the die. I've now switched to hornady new dimension and dillon dies and problem solved. I also gotta say those hornady dies are amazing and cheaper than dillons too.