What are the general advantages of Natural Wool Insulation over Glass or Mineral Fibre Quilt products?

The general advantages of wool insulation against glass or mineral fibre quilt products would be:-

1. Environmental issues, using a renewable resource to produce the product, while most glass or mineral fibre companies do state that they can potentially recycle their materials and reform new insulation from the older product, due to contamination of materials during the demolition process, this rarely actually occurs.
2. Wool insulation gives good thermal and acoustic performance, i.e. when looking at the costs, we would not be comparing against the lowest cost glass/mineral wool insulation, e.g. many of the lowest cost glass/mineral fibre insulation give a thermal conductivity of around 0.044 W/mK, so these lowest cost versions would not be equivalent in thermal performance. 
3. Wool insulation can be exposed to comparatively high levels of moisture with minimal detrimental effect on its thermal performance, therefore in real life conditions where moisture levels will vary from those of the official lab test it give similar levels of thermal performance to its declared value. Glass and mineral fibre insulation can have quite high reductions in thermal performance with only relatively small amounts of moisture within the material, therefore in real life performance may not be as predicted if running u-value calculations based upon declared thermal conductivity figures – in reality in many construction types, its extremely difficult to get a perfect vapour seal with a vapour barrier (due to the laps and various penetrations due to fixings and services), so even with a VCL on the inside of a product, it will likely still be exposed to moisture vapour during the building like.