All you need for a 550 is a set of dies and the press. If you own the dies just order the press from Brian Enos and you get the caliber conversion. Your done. $439.95
SDB comes with proprietary dies. That is why a lot of us dont like it. Price with dies is 379.95.
So you save $60 going with the SDB if you already own dies for your chosen caliber. Otherwise about $40 gets you some Lee dies. Don't buy the 4 die set. Get the Deluxe three die set and add a taper crimp die. That is MY preference and you did ask for advice.