I think the answer depends on how you go about increasing the fat adaption, if you are using diet for say keto or carb depletion then the fat adaption likely comes at the expense of glycogen dependant power production. If you are increasing fat adaption using long base or intermittent fasting rides during base then the % contribution of fat could potential increase your FTP, the percentage contribution at FTP is likely <10% so its probably not going to make much of difference, where it makes a bigger difference is in glycogen sparing in the Z2 range.
