Still using GG4 - seems ok so far.
I have a theory that GG4 thins the water down for slightly faster drying whereas the other product sounds like it thickens the water.
If it's come from the print industry then it will be designed to stay on the glass/printing plate as long as possible.
Could be completely wrong of course, I usually am.
I tried to compare the shape of a bead of water yesterday with an additive and without but didn't have much success - probably need a more scientific way of studying and measuring than I'm ever likely to have.
I wonder if my daughters school has any apparatus that measures surface tension, hmmmmm (strokes chin).