For starters, there are restrictions on the use of the Double Irish structure that generally limit the benefits to IP-based companies (i.e., technology, media, etc.), which is why most of the companies structured this way are technology companies.

Manufacturing companies would derive little if any benefit from the Double Irish structure, though this depends on the circumstances of their businesses.

Also, in regards to Iraq and Afghanistan, Ireland does not maintain treaties with either nation, so there is no special low rate that would shield such income.

(Sorry for the late reply; I don't read HN every day.)