With the first attempt at default settings the ZRemesher nailed it pretty much immediately. The only problem areas were the loops around the lips and under the nose. It should be noted that these are only considered problematic if we were looking for animation topology. For a still render it would have been bang on!
However, as I WAS aiming for animation topology I used the ZRemesher Guide brush to draw to sets of guide loops for the ZRemesher to follow. With them in place another click of the ZRemesher at default settings produced a fantastic result...there are still a few areas that would require some tweaking but like I said I fed in really messy topology.
It also only took about 40 seconds to calculate!! On a side note, I have also tried out the new Trim Brushes and they are amazing, perfect for cleaning up sculpts and cutting edges for hard surface sculpts.!
Right that's enough Zbrush spamming for now. (well, maybe)