Finally got a stable working FPU which is compatible with printf. I was surprised by the amount of maths used to print a floating point number. I have new wrapper functions now which replace the 68000 FP emulation code provided with the gcc compiler. This means that math functions are now sent to the FPU without requiring further code changes.
Using the framebuffer of the Gameduino Dazzler I was able to produce a really nice HD mandelbrot set. The calculations run a lot faster now with the hardware FPU.