It comes down to need. If you need more than 500rds a week, then a 650 w/ case feeder is probably the way to go. If you load for multiple calibers, a few 100 at a time, then a 550B is more economical & easier to use. The 4stn thing, not important for rifle rounds & not that big a deal for pistol rounds. You just don't get a powder check die for handgun. There is NO speed advantage to auto indexing, the speed comes from using a case feeder on the 650. Yes, I load on both & the 650 is a great piece of gear, but 90% of shooters just don't need that much machine, including me.