There is another product called insulfoam aswell.
I will keep you posted.
I was a bit curious so googled and found this info on insulfoam (you have probably seen this already). It's a liquid that expands into a foam. NOt sure though what insulfluff is, it sounds as if it is some type of loose material.
http://www.insulfoamsolutions.com.au/Pa ... rview.html
I will say this, as someone who has had to have all their plaster taken off their walls, it's a very expensive exercise. Make sure you are really happy about having this type of insulation because it seems that you may be saving the builder quite a bit of money, if that's the case they should be throwing something extra in for you and now might be a good time to negotiate something.
Someone on Homeone may have a lot of knowledge about this product and you may be getting a better product than those of us with batts, but this is a mistake by the builder (am assuming that this was not the original type of insulation they would be using) so make sure it is the best option for you.