Hi Avare,
Thanks for answering my question. Here is another one.

How much better, in your opinion, is a 4" 36 kg/m3 panel vs 96 kg/m3 panel of identical thickness ?
Pricing for the 96 kg panels is like R100 per inch ($13) compared to R25 (slighter over $4) for the 36 kg/m3 panels.