I was wondering about the use of XML in active game data management out there.  Are any of you folks using XML ORM or DBs in your games for any reason?

I want to develop my game to use XML files to load data from, for ease of end-user modification or expansion.  I just cannot decide if I want to read the files in once (or as I need entries) or if I want to read them into some sort of DB in memory (by DB I mean an XML DB or Mapping solution like Hibernate).  What I cannot answer is whether this approach involves too much overhead compared to an approach based on read-into-memory-and-leave-it approach using a SAX/DOM parser.

Any thoughts on this?  As a background context, this game is a tactical wargame, not a twitch-based or heavy 3D game.