Building a false wall to separate bathroom from one bedroom, looking at which type of acoustic insulation to put in the gap. Retail prices- Rockwool 100mm slabs are about 4 times the price per cubic metre than Knauf 50mm acoustic on a roll. Anyone got any views on the performance difference? (There are other parts to the sound reduction- acoustic board on one side, cement backing boards on the other, might even splash out on green glue)