pros and cons: XML vs JSON

Thanks for all the responses. These pretty much confirm my initial impression that JSON was the better choice but I was afraid I was overlooking something that would tilt the scale back in favor of XML. A server-side conversion to JSON is no problem (I already have code that does that). Regarding belltown's alternative idea of passing to the Roku only XML that had been pre-processed and simplified on the server (e.g., small chunks and without namespaces), I agree its feasible but I think it would have 2 disadvantages: (a) much harder to write, debug, and maintain the server-side code and (b) a much heavier traffic load on the server due to the increased frequency of requests. It also runs a risk of introducing response delays that are visible to the user.

I'm going to go with the "convert to JSON" approach.

Thanks again to EnTerr, TheEndless, and belltown for the feedback.