I've been using my own manual ordering system, which has worked quite well, since Apple Country Photography began. I still use such a system for my regular portrait, sports, and individual clients as it gives us both the most control over the finished product. However, the back-end engine has been changed from being a static Photoshop-generated gallery to a SmugMug custom gallery.
Why did I do this? Well the initial impetus was that I needed an online ordering site for large events (e.g., weddings and fundraisers) where many people would order and a paper ordering system would be too time intensive for me. After searching many different options, I settled on SmugMug's Pro account because they have, by far, the best client experience of anything else I reviewed. They also very recently upgraded their papers, so now they are using Kodak Supra Endura paper on their premium prints and I only offer premium prints. Now I can offer a fulfillment system whereby you can order prints with a credit card, you handle the crops, and they get printed and sent directly to you.
For my individual clients, the SmugMug gallery is just for viewing and you cannot order from it. You still use the paper order forms. Prints from my Apple Country Living Galleries also have a manual paper ordering system since I don't get overwhelmed with requests. These images all get processed by Miller's.
In general, I think this will make a much better experience for my clients. I hope you like it. Let me know what you think! I have the Pro Account for one year, so I'll reevaluate the system next year before my account expires.