For my first 9 years or so of reloading I used a 550B and it did well. It turned out some pretty good precision rifle ammo but it was a chore to do pistol and carbine ammo.
I decided to get a Forster Co-ax single stage for precision ammo and planned to get a 650 for pistol and carbine. I found a good article where a guy reviewed a Loadmaster, 650, and Lock and Load (which I of course can't find right now for you). Bottom line was the Loadmaster lost out to the Lock and Load and the 650. The 650 and the Lock and Load both had nice features over the other and I ended up changing my mind and buying the Lock and Load.
Dillon has a great warranty and a good product, but I was always disappointed with the (lack of) primer control on my 550. Also, the 650 and 550 require replaceable toolheads for each caliber conversion which the LNL doesn't have (just simple twist out bushings that are relatively cheap). The LNL also only advances halfway per motion (up or down) of the ram which makes it less likely to have powder fling out compared to the 650 where the shellplate rotates the entire distance at once. 650 requires the Dillon buttons for each caliber, etc. Changing out the powder system with the Dillon is also more troublesome with the 650 compared to the LNL. All fairly minor stuff though, admittedly. I went with the LNL mainly because I do a wide variety of calibers and switching between calibers on the LNL seemed easier and cheaper than the 650. You would be fine with either one, but I advise against the Loadmaster.
