It hasn't even felt like the rainbow rate was increased for me. Out of 12 10+1 pulls on the banner I got 1 Cloud, 1 Barret and 1 Tifa, plus 1-2 off banner rainbows. I had 2 pulls in a row where I barely even got any golds. I did pull 2 more Barrets from tickets at least, so I used 3 of the banner currency for his prism and STMRed him.