A 550 is a good press, I used one for about 14-15 years, I still use it to load .44mag, .38, and things like 30-06, 6.5x55, for $390 you did good assuming it came with all the stuff it's supposed to.. large and small primer pickup tubes, large and small primer drop tubes, large and small primer bars, at least one tool head, and the little thingy that you use to index the shellplate, and the aluminium cup to catch spent primers. And don't forget you can put a casefeeder on a 550, but there is a drawback...If you plan to load rifle cases on this press forget about the casefeeder, I asked dillon about this before and they told me that it takes about an hour to install the casefeeder and to adjust it all up. If you want to load rifle calibers, you'll have to take it all off.. The strong mount? That's up to you..I loaded on the 550 sitting down, and it worked fine. I rigged a bbq light up on the press, so I could see if the cases had powder in them before I seated a bullet. With the 650's I went with the strong mount and the bullet trays, and a powder check on my 9mm and .223 toolheads. You have to stand to load with this type of mount, but it works fine, I was kinda worried about this at first, because I have a knee replacement in my right knee, it turned out to be a non- issue..The roller handle, especially on a 650, is nice,too..