trimming bottom leaves an tiny branches won't really stress the plant, but it will focus the nutrient and water direction to the top of the plant making both more plentiful for the top colas. Usually in larger plants the bottom and middle thin out naturally as flowering starts and progresses so you would lose most of it anywars. But if it occurs naturally it will actually drain energy from the plant, if you do it yourself its like helping the plant along, if you catch my drift. I take those tiny bottom branches and make clones out of them for future grows...... not bad if you could manage it?????
Peace