I have used them, still have some. In order to make them float a 4" frog with a frog hook, I had to mix 1:1. You read that right, 1:1.
You can go 1:4 or so if you just want to float tails. The micro spheres will stiffen the baits, and will make them white (unless you add a ton of color, and, of course, the baits will NOT be translucent), and you definitely need to have a good mask on when working with them.