Sally, the building you describe doesn't fill me with fear!!! What some posters on here have trouble coming to terms with is risk appropriate solutions......well I suppose it's only been with us for 10 years so it's early days!
Perhaps someone should ask what the store is selling, wet fish or candles, could make a difference in my humble opinion!!! There will always be a risk of a fire occuring but the rate of heat and smoke development may vary from one store to another.
Construction, linings. ceiling height, able-bodied occupants in the offices etc, etc....perhaps these factors should be considered too.
It may be possible to consider early warning by the use of automatic smoke detection and live with the single exit?
Or alternatively we can hug the guides again...the world will be so much safer if we do.
Can you e-mail a simple plan of the building and some more info?