The 550 is probably the way to go. I won one at a pistol match in '87 or '88, and it has more than paid for itself in time saved. The manual indexing is no big deal, just get into a rhythm. I started with single stages, then bought a Square Deal (first year production) and proceeded to work it until it broke, but by then, I'd won the 550B with ammo loaded on the Square Deal. I've had the 550 ever since then.
I used to load on a single stage, even casting my own bullets, but had reached a plateau and couldn't progress until I was able to load ammo faster and more of that. I quit casting my own and started buying bullets instead. I did get a lot better, coming in 5th in my class at the '89 USPSA Nationals. That was a long time ago, though, I have nothing else to hang my hat on.
