Do you have experience with Microsoft XNA, what are its limitations? Working on a MMORPG game concept that requires a dynamic map and environment.

The project is in C#. I’m pondering on using ( http://en.wikipedia.org/wiki/Microsoft_XNA ) to cut down development time. Have you used it – or know more details about it’s workings?
What are the limitations?

Dynamic map – means a map that although is texture and model based, it can be changed (in terms of model shape etc) in real time by the game client.

Cheers. Kudos for general tips, hints etc.
If you’re curious about the project check https://sourceforge.net/projects/etherianlife/
You’re welcome to join.