I have a 650 and a 1050 (non-super).
I use the 1050 for 223 and 9mm, for the simple reason of the primer pocket swager that is built in. This way I can use range brass without having to swage it before putting it in the case feeder. Also, for 223, the Dillon carbide sizer is great. Not only is it very smooth it is also very close to being a small base die, which is another plus for using range brass from unknown chambers. For my 9mm, I have a bullet feeder also. I can load 9mm as quick as I can work the press handle. I preload several tubes of primers and start in. Get a Bullet feeder and an automated way to fill primer tubes. The only low alert use is for the primers.
The 650 gets used for all my precision rifle loading. I use Redding or Whidden dies and Whidden floating tool heads. Makes great ammo! I do not use the powder dropper, I take the brass off the press at the seating station, wipe off lube, add powder (the autotrickler is waiting on me to get the next round ready) and then replace and seat a bullet. The one thing I don't like about this, and one of two reasons I got the 1050, is with the 650, to seat the primer you have to shove the handle forward past neutral. This and the swager are why I got the 1050. Loading long VLDs in standard magnum rounds (7RM and 338WM) the seating die can get finicky and not let go of the tip to allow round to advance. If it's not standard, get the wide base, case feeder, Whidden tool heads if you are going to do precision rounds, and a bullet feeder if you are looking for high volume. Uniquetek makes a lot of nice add-ons.
The 750 seems to have gone to the sliding bar like is on the 1050, rather than the wheel from the 650 which is a huge improvement.
I got my 1050 second hand off Enos' site. The individual was a high volume shooter, so I have no idea how old or how many rounds it has loaded. I've had it for 15-16 years. I got my 650 a few years before that.