the big benefit as I see it is that if it doesn't help things, it can't hurt, except maybe create an intake flow restriction (for the air charge cooler), because nothing is being injected into the engine, and therefore you don't have to map for it at all. And one would really only be using it during the summer as far as I can see.
I have my doubts about intercooler sprays though. We've just hit the monsoon here in Korea, so while driving the FMIC is basically under a constant barrage of a LOT of water. I measure intake temp right after the intercooler - the most I see in dry weather is one degree colder than ambient. I think I saw 1.5 degrees colder at one moment during the rain.
Maybe it's because water doesn't exactly like to evaporate in 100% humidity. So in that case, a water spray might be effective in Dubai, but useless in Singapore or Hong Kong. Pretty damned humid in Seoul during the summer as well - sometimes it's really not that hot, but I have to have the air conditioning at home and in my office running, just to dehumidify the air.
And as far as a CO2 spray, I think distance from the nozzle to the intercooler is critical - the further away it is, the less cooling you get. Like with a air spray can duster. Near the nozzle, you'll get a cold burn. But twelve inches away, it just isn't that cold.
One thing I can't sort out from the website - if one chooses to only use the air charge cooling unit...where does the CO2 vent to?
as far as the environment, could be worse...you could decide to use Freon gas for extra chilling effect - blowing kilograms of it straight out into the atmosphere