You can use a progressive press similar to a single stage. To do this you only put one case in and go through all the stations until you have a finished round. You can also do just one station and remove it to put in a loading bock just like a single stage but that takes a lot of time to do. It is best to load one case at a time when you are developing a new load. Then you can check everything twice for each station to make sure it is right. One case at a time also is good to try to find out where a problem might occur to correct it.
Progressive presses are more compicated than single stage presses are. One of the biggest problems I see with people trying to work up loads on a progressive is the tendency to want to make a lot of a single load to test. It is best to not try to make more than 10 rounds for each change in powder you are trying. Who wants to pull a bunch of bullets because a load you made isn't going to work for your needs. Even once you think you have a good load you might not want to make no more than 50 to see how well it burns. I don't care for very dirty loads in my pistols. Often when using W321 powder just adding .1 grains more of powder will not affect accuracy but will make it a much cleaner burning round.
The SDB press is rated by Dillon at 400 round per hour. The 550b is rated at 550 and the 650 with case feeder is rated at 800 to 1000 per hour. I tend to load slower to be able to keep up with what is going on. The 550b is also a manual indexing press. I like it for working up loads since I have a lot more control with it compared to an auto indexing press. Everyone with a progressive press is going to have different ideas about what is or isn't good about each model out there. There are also many people that feel a progressive press is something nobody needs or should have. To each their own.
You can start out reloading on a progressive press and many have done just that. You do need to be more aware of what you are doing and not get carried away when you start out. You have to develope a system that works for you. Always check the powder level visually before you place a bullet to be seated. Learn what the handle feels like when you have seated a primer properly and what it feels like when one doesn't feed like it should. These two things will save you a lot of headaches later on.
Progressive presses are best used when you are loading a lot of ammo and you are not changing the components. A single stage is better when you are loading to get the most you can to match your guns. There are reloaders and there are people that load to get that magic round we all dream about. You just need to think about which you are at the moment. Even this opinion changes with time.