Well I thought I knew exactly what we were going to do for cavity wall insulation years ago, but just before placing the order for the fibre batts I (re?-)discovered blown beads (Ecobeads). I don't know if the Ecobeads have got better in the last 2-3 years since we decided on Knauf Dritherm Ultimate 32, but they look quite attractive. I got some quotes and the price for Ecobeads installed is essentially the same as the Dritherm material cost. I'm finding it difficult to make up my mind now.