I read an interesting1 tale about a fire officer (in Wales I think) who, upon finding one of these, instigated a drill with the staff. he took a football, placed it in a random1 position in the framework, and then during a drill recorded the amount of time it took to retrieve the ball. Owing to the time it took staff to retrieve the ball, a prohibition notice was immediately1 placed on the use of the equipment. Basically the staff were having to travel all the way through the equipment, in a long 'U' shape. The problem was minimised by the creation of exits from 'scary corner'.
I have dealt with one myself, and the standard found at the time was a real worry. Had I visited in todays "hang 'em high" climate I am sure they would have been prosecuted, quite deservedly so too IMO.
We also need to remember that fire retardant does not mean fire proof, as much of the research has shown, with the vertical surfaces leading to rapid fire spread.
My personal opinion is that these places are a very high risk unless the management/training/design of equipment is first class. Which is hardly ever the case. I also believe that consideration should be given to silencing that
The Chiltern Fire document is definitely worth a look, with some good advice for anyone looking at these things.
1: Not really.