Transport into the mitochondrial is carnitine independent and their oxidation is fast. Most studies have use 30g of MCT's to avoid GI distress. For results of a recent study, see Van Zyl et al. Premise is that by consuming less CHO and more fat, you get lower insulin levels and thus more fat released. However, this is too simplistic.
Endurance training does.
Thus performance is not enhanced. However, the training intensity while on such diets is low. Lambert et al. Muoio et al. 7 days on each diet.