Thanks for all the replies. Just the kind of information I was looking for.
I'm still leaning toward the SDB. Here's why.
I'm not a competitive shooter, nor a really high volume shooter otherwise.
Maybe 4-5000 rounds per year, or a little more. The thing is, I like to keep
a lot of ammo on hand. I have accumulated a lot of components; powder,
primers, cast bullets, and brass over the last 15-20 years. I
am subject
to consuming a thousand rounds of .38 special in a month if I have it on hand.
I have very little plinking/target .38 special on hand now. Mostly defense ammo.
I probably would load five thousand rounds of .38 special before I even thought
about setting up to load anything else. I have several thousand rounds of .45 ACP
factory ammo on hand, and maybe 2000 rounds of .45 Colt. Maybe in a year
I would think about getting a conversion kit for .45 Colt.
For the first year, my main concern would be converting a bunch of that .38 sp brass,
Bullseye powder, and small pistol primers into loaded ammo.
I figure I can get into the SDB with the few options I would want for $425
or a tad more. In another year, if I am still around and want to, I could spring for
a .45 Colt conversion for around another $100. The 550 would probably
run at least $100 more with options. Yep, I am tight. Can't heppit. Grew up
having to pinch pennies.
Space is a concern, and the SDB appears to be a little more compact.
There is a certain appeal to ordering the machine in .38special, bolting it
to the table, setting the powder dump, making minor tweaks to the dies,
and churning out rounds almost immediately.
Haven't really decided yet.