Congrats - I just took the plunge myself. I had owned and reloaded with an RL550B probably 16 years ago, I reloaded 9mm, .357Mag, and .44Mag. We had kids so I sold off my reloading equipment, but now that my son is 16 and I'm starting to shoot again (I only shoot .45ACP now) I decided it was time to start reloading (ammo prices have gotten ridiculous!).
I'm only doing .45ACP now, but I plan on adding 9mm for my wife's M&P, and .357MAG for my S&W. So far I've only reloaded a couple hundred rounds, but I'm loving it.
Enjoy your new Dillon - I know I am!