I think you mean marine goop, that is the same as all the other goops/shoegoo etc, except it has some UV protection added, which you will also find in some of the other goops and e6000 versions.
As to spraying penetrating the fabric, it will do this very well, it is a function of how thin the liquid/mixture is. The thinner it is the more it soaks into the fabric, bringing with it the rubber compound. There will be no difference between the penetration of a spray and manual application, as long as the amount and thinness of the mixture hitting the fabric is the same. With spray you may have to increase the thinness to compensate for some evaporation while spraying. Anyway the ratios I used penetrated extremely well.
Yes spraying has some waste, if you use an airless gun this will be very minimal. Manually applying with foam, brush, roller etc, will have waste too, be very time consuming and have more weight increase for the same results because the application will not be as evenly applied. There is also increased exposure time to fumes and risk of skin exposure with a manual application. But either way good precaution and protective gear should limit any health risk. I just see spending an hour face deep in fumes vs 5 mins spraying perhaps with a gentle breeze to clear the air as obvious to me which I would prefer. Foam is still a good idea, perhaps if you used a pole as well it would be safer and easier.
As to foilzone going and losing knowledge I wouldn't worry. The people mostly still exist
Just ask here and you should find an answer.
Koala Coat #25? do you know what the active compound/rubber is in it? silicone/sbr/pu?
Looking at their website Kamikuza might have a laugh http://www.koalaproducts.net/cleaners.htm
Koala Products. Koala Plastic Polish, Koala Cleaner, Koala Kamikaze, and Koala Sealer ... Cleaner, Koala CheetahShine. Koala Coat #25
What is the difference between a kamikuza and kamikaze again I forgot ?