I started out reloading with a used single stage RCBS press. I wanted to learn how to shoot a handgun and I knew I could not afford to do that using factory ammo. I am very patient about most time consuming hobbies I have, but I hated how long it took to load one box of shells. I upgraded to a Dillion 550 because I already had several sets of RCBS dies and I also thought I might load for a rifle at some point. ( I had considered the Square Deal B). After a short learning curve I was totally happy with the new progressive press. I load 45 Colt, 45 ACP and 357. I use Unique, Win 231 and Alliant 2400. I have toolheads for all calibers, but use the same powder measure. I have never had a problem with the powder metering accurately. As someone else said, changing between primer sizes is the worst part of caliber swaps. I found out that the primer feed must be adjusted between large and small primers. I believe that I turn the adjustment screw back and forth 1 and 1/2 turns between the 2 sizes. I would never go back to loading pistol rounds on a single stage press. I don't load that many rounds at one time. I focus on exactly what I am doing while reloading, watch everything, and load 2 boxes at a time. Then I reload my primers and go again if I need more. I also seat and crimp in 2 different steps.