I haven't used one to escape , but be careful what you buy. I know several of them have been recalled because when the filter get full/stopped up, it can become very difficult to breathe.
After several fires in Baton Rouge, they have been on the news quite a bit recently. The company I work for is going to be purchasing one for everyone on the floor. Not too shabby I think. At least we're learning from what's happened around us.
The Evac U8 smoke hood is a decent hood, although uncomfortable to wear. It does seem to be popular among office personell wary of potential fire hazard. And they are not too terribly expensive either. About $60 form several online stores. Most sites offer discounts for bulk orders. You might read some independant reviews before purchasing.
--Luke