I think it depends on how you run the war room. The way I prefer it is no off-topic conversation, no distractions, inside voices, and a lot of respect for your co-workers. Also, you need to provide convenient nearby meeting and lounge spaces so that people who want to do those things can easily do it elsewhere. I think that's a great environment for focus.

It takes some commitment to make it happen. Without everybody committing to a low-distraction workplace, volume is definitely the default. But I think the benefits of a team environment make it worth the effort.