15 April 2015
Thanks for posting the question in the forum. Would you mind explaining what do you mean by "improving maintenability" and why do you think DTS data sources would help you here?
XML brings best flexibility compared to .NET and DTS data sources. In fact other two flavors do not enable any kind of in-template scripting such as XPath. So if you need this kind of flexibility (scripting, functions), then I strongly suggest that you stay with XML. It might happen that we will add scripting for DTS and .NET object data source as well but there is no telling when this will happen.
You should also know that we are preparing some new features in version 2.3, such as Preview and Friendly Names/Descriptions and these will be in the next version (2.3) only be available for templates with XML data source.
In other words, XML has proved to be a good choice for data source, it has many good characteristics and we see a lot of our customers chose to go with it. This is also why we see it as a first class citizen and in the future it will probably be the first of the three flavors that will enjoy new features.
Let me know if this helps you.