A great way to sharpen your processing skills and learn new techniques, Graham.
I prefer the last. The others seem a bit indecisive - compromise between reality and design.
Of course you have a model release that includes permission to carryout this sort of manipulation...
The edited versions are interesting, almost disturbingly so.
I was not expecting the colour in your edit and I laughed when I scrolled and saw the first one! I think they are definitely interesting and the last one is particularly artsy. I like it!
I love the artsy look as Rhonda puts it, Graham...but #1 (and perhaps the others too) -- you need to go to select the round selection in the eye and then go to Hue and Saturation to brighten up the eye a little bit and give it a pop...