I just got my 550 oh 6 months back. The tech guys at Dillon told me that most of them ran the 550. That kind of sold me on it. IMO it is also easier to learn on the 550 when you are switching to a progressive because it is NOT auto-indexing. You move it, so you can back it up and correct something or keep it where it is and adjust dies when setting up. They have a great warranty too. I have a couple of RCBS single stage also, so not just a Dillon guy. I don't know about what the other companies have for warranties when you get away from these two brands. Probably the same, but I honestly don't know. Anyway, good luck with whatever you decide.