It is not essential to wear boots across the Sandakan track but I highly recommend good quality comfortable footwear. My boots are 100% water proof. (At least they are until the water comes over the top) They are also a light weight Gortex construction for quick drying. They have an aggressive Vibram flexible grip and sole for better traction on the track. Companies will push their own brands and preferences and attempt to convince you of the benefits. My suggestions are that the boots must be comfortable, be at least one size bigger then you would normally wear. This will prevent you from getting sore toes on the declines; your feet can also swell causing discomfort. They should also be light weight quick drying and have a good flexible and aggressive grip. The track is harsh on boots so do not risk old or suspect boots. I have found Aku and Scarpa boots to be the best for me.