....there was an architech who was against the idea....
Is this the same guy who claims the world is flat and the sun is at the centre of the universe? I've seen him too.
Mineral fibre is preferable to foam or poly beads. Fibre would not cause any problems but foam or beads could be more at risk of causing pockets of dampness.
Please hurry up and insulate your walls as otherwise the earth will melt into one big bucket of tar. Also stop using anything with an engine, and snip your electricity supply and gas pipes - the heat from Chinese factories will keep us all warm for the next few years.