Here's a pic from a dude that did a side by side on another forum. The 3 plants on the left were grown naturally, and the 3 plants on the right were defoliated. The natural plants grew almost twice as much bud weight than the defoliated plants.
Note that the defoliated plants ALL have SMALLER lower buds, despite the fact that the plants were defoliated to "provide more light to lower buds and increase bud size and growth". If bud development was dependent on light hitting the bud sites, than the natural plants should have smaller lower buds, however, they are CLEARLY larger, despite being covered by fan leaves.
This photo clearly shows that the defoliation of 3 plants REDUCED lower bud development compared to 3 naturally grown plants, and therefore, is NOT an effective technique to increase either yield OR lower bud size.
Fan leaves are there to serve the plant and the buds, and their removal WILL have a negative impact on your plant. Period.
Best of luck, regardless.