At the moment, .45 ACP is about all I load. And I load a LOT of it! So, I have a Dillon 1050 set up to crank out better than 1000 rounds per hour.
I have a few thousand 9mm loaded for my SIL's XD9 but that came off of a Dillon 650 and he doesn't shoot much so I won't be making any 9mm in the near future.
I am about to start loading .40 S&W for my wife's Sigs. That will also be done on the 650. After testing a few loads, I plan to load about 5000 rounds.
As soon as I empty out a couple of ammo cans, I also need to reload about 10,000 .45 ACP.
So, yes, I prefer just one caliber but I do have to make an exception.
"No matter how cynical you become, it's never enough to keep up." - Lily Tomlin