I've had an XL 650 for over fifteen years now. I load a fair amount of ammo, all calibers from .32 ACP to .35 Whelen. I load only for myself; not commercial sales.
The XL 650 is the perfect machine for the loader who shoots up to - 3000 rounds a month, I'd say. I don't load that much, but it wouldn't be hard to do. Dillon powder measures deliver reliable and consistent drops of powder for pretty much everything I shoot. The most questionable loads are those with flake or extruded powders, and the variation is within limits for everything except ragged edge maximum loads (away from which I tend to shy.)
The Dillon Super 1050 is a great, high volume machine. However, it is not as convenient to change calibers as the 650 or smaller Dillon machines. My understanding is the 1050 is used as a dedicated, one caliber machine for commercial loaders.
In the spirit of full disclosure, I've never used any of the other progressives. After buying and using the Dillon 650, I've never felt the need.