I have done that style of training twice: once in a MOUT (Movement over Urban Terrain) site which had been setup to look like a U.S. embassy. We were triaging survivors of an embassy attack.
The second was a blue team training area focused on securing, protecting and removing victims of a VBIED attack overseas.
Both were high stress and high intensity. If done right it will get you totally sucked into the scenario.
I wrote Full Scale Exercises for our local CERT team as well as for the MABAS training. It was a lot of fun.
L