I started my progressive journey with the Hornady L-n-L AP. It sat on my bench not seeing much use. It wasn't as intuitive as I thought it would be. When everything went crazy back during covid, I had a guy that offered me more than I could pass up for it. I ended up buying an XL750 with case feeder and have been in love ever since!
I have loaded .223, 9mm, 300blk, .357, and .38 special on it. I swage off press with a Lee APP so the swage on press wasn't important to me.
When it comes to the progressive world there's a reason Dillon has been around for so long. Their customer service is also second to none!! Need parts for a press, give them a call and you have them in no time! Have an old press that needs updated, is missing parts, won't function right? Send it to them and you get a press back at your door that's like brand new for little to no money!
I still load all my bolt stuff on a single stage, but if it's something that I'm wanting to pump out, it gets done on the 750. I know guys that run match ammo for PRS on their 750, I just didn't want to go down that route. I don't have the volume need for it.
I've really thought about picking up a 550 to do some precision loading on as I've read a ton of great reviews on guys using it for that.
It all comes down to what you want to spend and how quickly you want to load rounds. I may not be right in my assumption, but I believe that the 750 with a case feeder is at least twice as fast as the 550.
I timed my self once when doing some 9mm, placing bullets on by hand, I averaged put to something like 400/hr. I wasn't trying to push it, just a consistent, steady handle pull.