The most annoying thing about Mr. MacMillan is how often I agree with him. I think the pleating style is personal choice but if you are going to wear a wool kilt hiking make sure the length is correct. You want this kilt to be at the top of the knee. If it is longer it can catch the back of the knee and it can be a dreadful experience. It is especially bad if the kilt gets wet.

To give you an answer to your original post though I think it is a toss up between a knife-pleat and a box pleat while hiking. Technically both have 1/2 the pleats facing forward. A box pleat does however have fewer pleats. If you are really worried about the way the pleats go then a reverse Kingussie pleated kilt would be the way to go. This way all the pleats face the rear and they meet at a reverse box pleat in the rear of the kilt.