I've got a Dillon 650. I've had it for almost 20 years. There have been zero issues. It's everything Dillon claims it is. I suppose they have a good warranty, but I wouldn't know. Absolutely nothing has given me any trouble.
Besides the well thought out design, speed of use, and accurate reliable ammo it produces, caliber changes are pretty easy.
The auto index places it well ahead of the 550, for my purposes.

I spent a lot of time at the Dillon booth at an NRA convention, trying out all their presses. The Square Deal is clunky and gritty by comparison, with lousy leverage. No way you could do bottleneck cases on that thing. 550 was OK, but, like I said, the auto index and extra die location on the toolhead really sold me. I did look at the 1050, but caliber conversions are a big headache.

Just my opinions here, but, I hope this helps,
Jim