I prefer the paste over the roll-on, as it will not become contaminated with blood, which could increase chances of spreading CAE in goats. (Herd is test-negative since 1998 and I want it to stay that way!)
I tattoo rabbits and registered dairy goats. I use the green paste, tattoo and then use the roll-on to push more ink into the holes. My tattoos last the life time of the animals and are clearly readable. Wear gloves as both the paste & roll-on are messy....tho it washes off easily.