“The first bushfire bunker to meet new state government regulations has been accredited in Victoria Australia” so reports AAP via Yahoo! 7News.
FireProofShelters.com.au looks to be at the forefront of this idea and their site offers a view of the product.
A couple of thoughts. If you can afford it why not have one installed. If you live in tornado country it could play a duel role. The larger version holds up to 8 people so multiple neighbors could share costs and use. During the winter the unit could be used for storage.
I cannot see a down side.