NRC panels replacing traditional insulation and its impact

Dear All,

We have a 360 kVA Kohler DG for which there was no sound proof enclosure.
Recently we are forced by our neighbours to have acoustic enclosure.

Have come across some specs and would like to know some more details
one supplier says his nrc fabric and panels are superior to rockwool, the traditional insulation material. His spec goes like this:

Fabric:
• Fire (Class) – 1
• Acoustics – 0.75
• Thermal conductivity (W/mk)– NA
• Climate (°C, RH) – 50, 90
• Light reflectance (%) – Color Dependent
• Green (VoC, RC %) – Low, 25

Panel:

• Fire (Class) – 1 & P
• Acoustics – NRC 0.97 (For 40mm C50
Mounting)
• Thermal conductivity (W/mk)– 0.07
• Climate (°C, RH) – 50, 95
• Light reflectance (%) – 80
• Green (VoC, RC %) – Low, 30

However I have this below spec proposed by most of the others:

Outer enclosure body of 1.2 mm thickness
followed by 64 kg density rockwool 100 mm thickness and perforated GI sheet riveted to panels.
Sound attenuators infront of radiator and fresh air inlet through natural draft

Could please throw some light on this comparison.

Thanks,