Gerry, it is obvious from what you wrote you know NOTHING about Dillon presses.
"Changing between 4 different calibers all with different primer types isn't really something you want to do with a Dillon often."
Have you ever loaded anything? Do you not know the .25-06 and ..308W used the same primer type? (LR) Do you not know the .44 Magnum and .45 ACP also use the same primer type? (LP)
The 4 cartridges the OP mentioned need just one primer feed (Large), and NOT the 4 different sizes you state. There is NO changing required.
"Changing out calibers from say 9mm to .45 ACP on a Dillon XL 650 with a case feeder is not a trivial task..."
Have you done this or just "heard" about it? Again based on what the OP wrote, 3 of the 4 cartridges he mentioned use the SAME shell plate and require NO TIME to change. Only the .44 Magnum uses a different shell plate.
If you had ever done it you would know that the casefeeder changes are equally non eventful.
"The other option is to buy 4 Dillon presses."
Although it would be nice to have, this is... to be nice just silly!!!
"And yes, I know folks that have a bench full of Dillon presses devoted to each caliber they shoot."
Well there it is, you really do NOT know anything about Dillon products. You give advise based on what you have heard!!!
T.