Sorry, I have no direct experience with the RCBS Proi 2000. RCBS produced quality goods, though. Hornady, too. Once you get one of these tuned up and running, I imagine you'd be well satisfied.
My personal satisfaction with the Dillion 550B is just about unbounded, and this certainly colors my opinion. I loaded quite a bit on a Lee progressive about 12 years back and was badly disappointed. It may have improved.
With the D 550B, you can turn out a lot of handgun loads for very modest effort. You say you don't care to load rifle cartridges now, but you may change your mind later. Again, I don't know the Pro 2000, and such may be possible with that, too.
If you wanted to stick with only one, or possibly two, handgun rounds, I'd suggest the Dillon Square Deal B, for economy's sake. For several, though, the 550B is very easy to change calibers, and you can use standard 7/8X14 dies--Either something you already own, or they can often be found used for low prices.
the Speer Reloding Manual #17 is a very good one, but you should always second source--Check loads before using them. Even the finest manuals have mistakes. Any fair-sized sporting goods store that sells loading gear and components has giveaway manuals published by the various manufactures, if only for their own products. And, you can find used manuals at a lot of gun shows.
Actually, it is very good, if you can afford it, to have BOTH a single stage press and a good progressive.
Welcome to the wonderful world of rolling your own!
Come back to H&R forum often.
Best,
Johnny