Thanks to all who helped me make my decisions with respect to my bike. In the end, I was very happy with my choice of bike and had very few problems with it apart from a broken seat post! I am still amazed at how well the bikes hold up to this event.
My Bike choice was a Salsa Cuththroat with a 100mm Rockshox fork. I used 32 chain ring and 11-46 gearing. 2.35in Vittoria Barza tyres. Metal brake pads and 160mm discs.
Having done the event now I think whatever choice one makes will entail compromises:
My bike was light and had a large triangle which allowed for a frame bag which I found very useful. This was great for portages of which there are a lot. The drop bars gave lots of options for hand positions, but I still ended up with carpal tunnel syndrome. I didnt have a back shock, which meant less stuff to go wrong, a lighter bike, but meant bombing downhills on rough roads was a challenge. It was arguably also less comfortable on the washboard.
I think, bottom line, for this event, to do it comfortably, one needs wide tyres (>2.3), Front fork and metal brake pads (mine lasted the whole event and Im 95kgs plus backpack), tubeless tires. Everything else is a compromise that will be an advantage in some areas and a disadvantage in others. I would not consider doing it with a rigid fork (Thanks to the forum for talking me out of that), or tires less than 2.2. I would probably have a 30 or even 28 front chain ring next time.