Had another play around. This time creating a pretty standard and cheesey flame effect. The second image demonstrates the way that you can really alter the look of the fluid just by fiddling around with the texture and shading settings, it's actually the same flame animation but with transparency decreased and the incandescence settings altered with. I'll upload an animation version of it shortly as it renders reasonably quickly. I think my issue with the last animation was that I neglected to alter the density settings in the emitter itself, therefore the the Fluid Shape was having do to much more work in order to to create something that looked thick.