I looked at the options available from just about everybody and went with the 650 complete with case feeder, strong mount, and powder check. I had a (maybe irrational) fear of ammo loaded on progressives for years, and never even considered one until I saw a 1050 with the powder check. It doesn't replace careful attention, and you can still look into the case before setting the bullet in place at station 4. Maybe redundant, but it makes me feel better.
The search narrowed to the 550, 650 or the Hornady. The 550 lost out due to lack of a 5th station, lack of a case feeder option, and lack of auto indexing. I cannot offer a good reason for passing on the Hornady, maybe I just like blue better than red.
Whichever you decide on, the bullet tray would seem to be a worthwhile addition. I didn't get it, but will order one with my first caliber conversion.