I actually wear Fantasy Fire quite often as it works really well over so many colours. I was actually wearing it when I found out they had changed the formula. And just a note, but you can see the colour shift in person I just couldn't capture it very well on camera.
For my base I used 3 coats of this vibrant purple from a brand called F.A.W.N. There was no name on it just the number 018. I have never heard of this brand before and I have no idea where I bought it from. Shrinkage aside it is very pretty.
While I don't have a comparison post, you guys can head over to Cosmetic Sanctuary and see her post where she does a detailed comparison of the two. Here are some of her photos so you can see for yourself how different it now is. New FF is on the left, old on the right.