I am sure that Roy posted something about this a while back. Need to do a search....
I'm not sure whether I have written anything on the forum myself, about waterless coolant!
I certainly know about it and am considering trying some, but I also have some Water Wetter which I was going to try at some point.
The idea is to aid heat transfer from metal to coolant, which is what the Water Wetter is supposed to do. If it helps great, and this is likely to be cheaper than the Waterless Coolant.
However, with either you don't want to waste it, so make sure the cooling system is 'top notch' first. So your radiator is new or very good, your hoses are all good, new rad. switch, thermostat, temp. sender, new gaskets where necessary and of course a new water pump. If the system is really good, you would be surprised how much difference it makes without any of these extras.
This is another example of where you should not try to improve something with third party things before making sure that it is functioning at its best in the first place.
Roy