Don't know a whole pile but would think the Quinn Lite blocks would be a good option - solid walls and better for hanging pictures, etc. (although you do need special fittings). Was the the SElf Build Expo in Belfast on Saturday and the Acheson & Glover (produce lite blocks also) stall promoted this as one of the big benefits of the lite block.
Obviously contact Quinn and ask about the sound insulation properties but I would think it would be better than stud. Would be interested as I am looking at the the ICF route also. Can I ask which ICF company you went for? Thanks.