Brian Enos, he has a forum and is great to deal with. You can also try Larry at Louisiana gun and reloading supply he is a member here and is located on Jefferson.
If you can find Ed's Reloading Supply on eBay I bought all of my Dillion stuff from him. You can go to Bing.com and type in Wii and a coupon for 8% off any eBay purchase comes up.
When I bought my Dillion the coupon was like 20% and I got a 650 for much cheaper than I could have bought a 550.
Now that I've been reloading for a while and having used the 550 and 650 I would have rather had the 550.
Also, if you come into Baton Rouge give Larry a shot on the 550. It might not be the best price you see but you are guaranteed the best customer service from some good people. I do a lot of business with them and anticipate doing a lot more in the future.
It's not significantly faster, parts are much more expensive, it takes longer to do a caliber change, the auto indexing has a tendency to slosh a little powder when indexing, and the case feeder is almost a necessity with the 650.
I could go on, but was hoping that would be sufficient
I have always bought my Dillon Presses and parts from Dillon directly, if you locate a used 550 press and need the .45acp conversion kit and die set, I have a used complete set, both retail for nearly $120.00, PM me if you would like to make an offer
I just bought a used Dillon 550b! A friend of mine called to tell me about a guy in town selling a Dillon 550b. Made a phone call and the deal was done. After getting messed over on the last deal, I have proof that things happen for a reason and good people are still out there. I got the reloader with .45acp and 45LC dies, etc/Dillon tumber/RCBS scale/other stuff that I don't even kown the name of/5lbs of powder and 5000 winchester large pistol primers, all of this for less than the "money in hand" deal. Thank you seller and buyer of that deal, without you I wouldn't have made this deal!!