XML configuration files have pretty much disappeared/become optional. It's all done via annotations nowadays, which are much less verbose since their context is implicit, and which are actual language constructs known to the compiler.
Annotations have the disadvantage of needing a recompile to reconfigure?
In any good development shop you make a change, your CI server picks it up, builds it, and creates a release candidate you deploy. Every change should be checked into source control and built by your automated build bot.
At that point the difference between changing an annotation and an XML configuration file should be moot. I'd think the annotation would be easier because you can still mess up the syntax of the XML file pretty easy (e.g. "Can you change the blahblah label to System & such?" That ampersand will hose your system when you get it to production).
But that's a tiny subset of what architecture astronauts try to label "configuration".