I think SmugMug works well if you live and sell your work in the US.
I started a SmugMug Pro a few years ago, and had trouble with the tax bit. Prints took a long time to deliver to Canada as well. The gallery pricing system is confusing to me. I'm sure it's powerful, but you need to spend a lot of time with it to understand how it works because there's a bijillion options.
The ordering interface was confusing to some of my clients. One fellow didn't know about the cropping features, and ended up with prints that were improperly cropped, cutting off parts of the images.
I downgraded to non-pro account, and do my printing and selling outside of SmugMug. Maybe it's much better now, but long shipping times to Canada is odd. B&H ships Purolator and it's rarely more than 3 business days to deliver.
Thanks for your feedback! Were you aware of the proof delay feature, which allows you to "approve" or change an order before it is sent to your customer? It would have allowed you to fix the crops before they went out.
You can read more about it here.