Welcome to the asylum and the forum. Looks like you're off to a running start with some great equipment. The SDB came out after the very early 550 that is bolted to my bench and I've always felt they were a good machine for a good value. As has been pointed out they don't offer much flexibility but you seem to know what you want, that's a good thing. It would be nice if you had an experienced reloader looking over your shoulder but If you'll read the instructions, read the instructional sections of your manuals and proceed with caution you should be fine. Dillon has excellent customer support.
Buy or build a nice, big sturdy workbench, I have a feeling you're going to need it. Leave room for a single stage or turret press for when you decide to load rifle rounds.
Now for some bad news: "reloading to save money" is an inside joke. Yes, it's possible but few of us have actually pulled it off. I recently loaded 2K rounds of 45ACP for about $2 a box but I cast my own bullets and I've been chasing the same brass and using the same 550 for many years. My 550 paid for itself when I was shooting 15-20K rounds a year shooting competitions so I may actually be saving a little these days but I spend it on more reloading and casting equipment.
The good news is you'll be able to load ammo better than you can buy to suit your needs. You'll also get to shoot more and you'll never again have to buy ammo on the way to the range. You'll also have a hobby many of us enjoy and you'll have the satisfaction of firing ammo you made. I still get a kick out of that.
If you haven't already spend some time reading the stickies and threads that interest you. Unlike the guy @ the gun shop we don't have anything to sell.
Life Member NRA, TSRA
Smokeless powder is a passing fad! -Steve Garbe
I hate rude behavior in a man. I won't tolerate it. -Woodrow F. Call Lonesome Dove
My favorite recipes start out with a handful of used wheelweights.