I have both, plus a 1050 set up for 223 only.
The 650 gets my high volume stuff, 9mm, 40SW, 45ACP, etc. The 550 is set up for large primer and stays that way. It loads my low volume stuff, 10mm, 30/30, 35 Rem, 45/70, 300 Mags, etc. Stuff that I only shoot a little of a year. Caliber conversions and toolheads are cheaper for the 550 and I don't regret having both on my bench.