I have a Dillon 550 which will load handgun and rifle ammo. I load for 6 handgun calibers. All dies are mounted in their own tool head,3 of them have dedicated powder measures,a 4th powder measure serves the other 3.
Someone already stated how easy the caliber change is one a 550. My understanding on a 650 the change of the primer system takes a bit longer. When I change from large to small primers I use this time to thoroughly clean this area of the press,so it may take me a bit longer to change over.
You will find that some people like Dillon,some Lee,some Hornady.
Just like some people like Ford,some GM,some Chrysler.

Then there is the $$ involved,Dillon is more then Lee. Then there are the extra toolheads,powder measures,etc. In my opinion the toolheads would be a must,extra powder measures a bit of a luxury. It took me several years to justify the $$ for the extra powder measures. However I did find them online for less than Dillons price. Just depends how deep your pockets are I guess.

If you know of someone nearby who has a progressive machine ask to see it in action. In my case I took my brothers advice for the Dillon, at the time he was shooting IPSC and he had 2 of them one for each primer size.

OK I probably got a bit long winded but hope this helps you.