I've read every single post on this thread in detail. I'll have been loading ammo for 60yrs this month. I grew up with STAR RELOADERS in .38SPL & .45ACP. My Father rarely changed them out to other calibers. We shot 100rds each of .38 & .45 for one of all others combined. With Father, 2 Uncle's, 3 Brothers and Cousins we went through A LOT OF AMMO. Growing up in the 50's/60's LEAD was free, or pennies a lb. Primers were bought once a year. They came on a skid by truck. Powder came in 20lb cans. Also by truck. My Dad's friend with an FFL received them for him. I guess he was the person they were ordered through too.
I'm going the long way around the barn. But what I'm trying to say is been there, done that, got a lot of t-shirts.
Used everything from the old dillon 300 on up through the 650. Even a 1050 once.
The dillon 550 IS NOT 37+YRS OLD. I bought my 1st house in Feb 1984. The dillon ad for the old 450 appeared in Guns&Ammo the next month. $185.00 w/ one caliber conv. ***. Sold to a guy for $180. I watched him buy every little upgrade & DoDad for the next 20yrs. Every upgrade loaded the press up, ie; it required more force on the handle. And that powder measure is an abomination. He blew up 2 6ixguns & a good rifle that I know of with ammo loaded on one of those blue presses. I'm not sure how many blue colored presses he had when he died 12yrs ago, but I do know he bought a blue shotgun press & at least one each sdb, 550, 650 & the same caliber conv. For each press. They just sucked him dry. I know in the right hands they can turn out good ammo. But they nickel & dime you to death & the caliber conv take up a lot of room.
I've had the RCBS Green machine & 4x4. I've worked on various versions of their 2000 press. Lee, If you can't say anything good, say nothing at all.
HORNADY PRO-JECTOR was a good try & It took the L-N-L to work out the bugs. The bushing die system works well if you pay enough attention to tighten die/bushing properly. And the dies in the bushing fit in the die box and stack on a shelf just like other quality dies. The shellplates just stack on a shelf. Most importantly it uses a proper rotating drum powder measure. Which is the most consistent you can get.
All things being equal start with a single stage, learn what each step is/does & then buy whatever you're willing to try. My RCBS RockChucker is 40+yrs old, my LYMAN Spartan a few years older & my HORNADY L-N-L is about 12 or 15yrs old.
Heck my MEC 650 is 50+yrs old & it's accompanying Super-Sizer is over 40yrs old.
Buy what you want, and good luck with it.