I have a friend,, who owns about 4-5 Dillon SDB presses. He loves his machines. They do exactly what HIS needs are. He's the kind of guy who appreciates good equipment,, yet also understands his limits & desires. He has his "regular use machines," and a "spare or two" just in case he wants to swap around something,, or if something breaks down & he wants to continue until Dillon can get him replacement parts. Plus,, he has (3) kids,, who he tries to make sure each one will have the same things once he's gone.
I own a SDB, with a couple of lower used calibers for the loading I need for those calibers. But I recognize the limitations of the SDB. (Proprietary dies, only handgun calibers, and they can't use the KMS Squared lights.) At one time,, I actually owned 3 of them at the same time.
I also own a Dillon 550. It's primarily used for a few of the rifle calibers I need a larger volume of ammo for,, and still allow me the manual checking of the steps I prefer to use in my loading. It can be a plus or a negative,, the lack of auto-indexing,, depending upon the current use.
Next,, I own a pair of Dillon 650's,, which I got before the 750 was introduced. Of my Dillon's these 2 machines,, which each one is set about the same,, except for the priming system,, (one large & one small) do the majority of my progressive loading.
Unlike my friend,, I use a larger volume of ammo than he does,, so I truly appreciate the 650's and the way they operate. But each of us have different needs or desires. The SDB is an excellent machine,, with a few limitations,, that most of us can accept. But in my opinion,, for volume, reliability, ease of operation, the ability of using the aftermarket KMS Squared lights, my 650's are the cat's meow. My opinion.
And I had the opportunity to "upgrade" a little when a 750 came available. I decided to just stay with my 650's,, and allow someone else to own the newer 750. I hope he's still happy with it!
Each one of us who own & use a Dillon have an appreciation for the machines we prefer. And each one of us enjoy the way Dillon takes care of their customers.
Hard to beat any Dillon equipment!