The 550 costs less, the caliber conversions are cheaper than the 650's. However, the 650 will crank out many more rounds per hour.
Rule of thumb on progressives is the more money you spend, the less actual time you will have to spend reloading. It's best to find a balance between available cash outlay and time. 45acp is right. Most of us do end up with a dillon...
A slow hit beats a fast miss.