This is so helpful everyone, thanks. I love the idea of customizing once I've spent some time in the saddle, but lots of swapping out of the gates feels a bit overwhelming. Seems like I'll know more about what I want after a couple hundred road miles.

Misandal, I was surprised (and psyched!) to hear that your LBS swapped out a compact for a triple for free. Do you know if they had a triple in stock, or did they really do the labor of disassembling and reassembling? I'm not sure my shop would be so accommodating. But it never hurts to ask...