Ok,, I will say I have 4 Dillons. Briefly,, I had 5 of them. I used to have 2 SDB's,, but sold one after getting a second 650.
Currently,, I have a SDB, a 550, and a pair of 650's.
That said,, I can say the above info on JUST 9mm & the SDB will be just fine. And,, as noted,, caliber conversions are pistol caliber only,,, AND you have to use Dillon dies & all. When I had a pair of the SDB's, I kept one set-up & dedicated to my .40 S&W match ammo. The other one,, I have caliber conversions that use the SMALL pistol primers. My 1st 650,, was purchased for & has only been used with calibers that use the LARGE pistol primers. The primer conversion is a bit more time consuming & all for me,,, so I set up my 1st 650 as a lge primer one, and used to let my SDB's handle all the small primer stuff.
Well, I got a good deal on a 2nd 650,, so I got it,,and set it up as my small primer machine. I haven't gotten all the different calibers yet,, to allow me to reduce my use of the SDB,, yet.
My 550 is used for rifle calibers, currently set up for .223.
I have several caliber conversions to allow me to easily swap things around w/o much trouble.
While some folks say to buy a different brand,, I can say,, after almost 20 years of Dillon use,, I can testify to their "No BS" policy. Even when it's not your fault,, they replace stuff FREE. PLUS,,, their machines WORK!!!!! If they do not,, their staff will PATIENTLY talk you through things to get it working again. And if new parts may be in order,, they will promptly ship them at NO COST,,,!
I was talking to Steve Hornady,, and showed him a picture of my reloading set-up. He commented; "That stuff is the wrong color." To which I replied: "No, it is not. When you have a total NO BS policy,, as well as the staff to help like they do,, then you can understand why my stuff is blue." He chuckled & replied; "Yes,, they do have good stuff,, and they are a good company." I then showed him several red items on & around my bench. We had an enjoyable conversation.
So,, in summary,,, YOU have to decide what will work for you. Your budget,, your space, and what your desires are. All progressive machines will do a volume of ammo. A SDB,, is a bargain,, and is a good quality machine. The 550 is a manual indexing machine,, and is the middle line machine for the company,, and I THINK their number one seller, due to versatility, and not having to buy just Dillon dies. The 650 is the cadillac for the hobbiest shooter. The 1050 is more of a commercial machine.
I for one,, love the casefeed assy, and the auto-indexing. And while the 550 now has a casefeed available,, the 650 does have an extra station. For that,,I like the powder check assy.
Lastly,, to answer your questions; No,, the Dillon does not weigh charges,, so you still need a scale. BUT,, powder meter very well & consistent in the Dillon powder hoppers. People who load and are TOP level competitors use Dillons,, and trust them to work properly. Money & titles depend upon them.