I did the 2008. Finshed in 221st overall. Thoroughly recommend it, the organistion was amazing, the scenery fantastic. The Costa Ricans made us feel incredibly welcome.
For 2009 they were going to make it a five day race, but haven’t been able to put everything in place, so they are keeping it at 4 days, with improved mechanic service and better hotels. Although I had no complaints about any of the hotels that we stayed.
If you decide to do it. Train twice as hard as you think you need to. Use a bike with plenty of mud clearance and make sure that everything on you bike is in excellent or even new condition and lastly, practice your Hike-a-bike, the first day is brutal.