I have found some additional information on this subject.
Installing airtight recessed luminaries We have switched to the Nu Teck boxes as well but dont double up the poly hats with those style. Never really questioned that before now that you mention it. But after looking at the document in the link I posted I really can see the validity of doubling up with the cool blue poly hat and air tite housings. The problem still stands that the poly hat is too small or the housing and both recommended to work together from the manufacturer.
