Lucas,
Great that you figured out a solution for your needs. I found the process of getting set up with XML painful as well. But I think it has paid off for what we needed.
The direct-mail portion of an already automated email and SMS marketing campaign we launched before using XML involved manually creating postcards through an increasing stack of customized Indesign templates for a highly segmented audience. The postcards were custom built for each audience group and data tables varied from 2 rows to almost 40. The large postcards had the table data on one side with marketing information on the other. The segmentation involved multiple templates by brand, messaging, etc. Data was manually copied from spreadsheets and then cellstyles were applied depending on the row data (highlighted rows, bolded text, highlighted columns in some cases).
This took about 15 minutes per card on a good day and often the table data was formatted wrong, which meant another round of processing for any card each time proofers found an error. Using this manual process and extra hired help we created about 1,300 individual postcard layouts during the campaign. With XML, an automated desktop system using Indesign and Automator, Applescript and Folder actions, we created over 9,000 postcards in the same period the following year, more accurately. In fact, we expanded and were able to use the same data to create sell sheets using different templates. We would have had to create Indesign templates regardless of manual or XML workflow. And the extra time used to flesh out the XML processing was more than recouped in the big picture.
We learned a lot that we can use for future projects, and I'm still a fan of the XML capabilities of Indesign, such as it is. But I agree with you there really hasn't been much of an improvement in this feature of Indesign over the course of several years, and the documentation out there can be useless and out of date, leaving us to seek answers in places like this forum one question at a time.