There is no pro to doing it within the atmosphere.
We could potentially put something at L1 to reflect sunlight. An "angular soletta" was proposed in Kim Stanley Robinson's Mars trilogy. In that case it was for the purpose of increasing insolation on Mars, but the same nonexistent technology could in theory apply to reducing it on Earth. The idea was nested truncated cones of flexible, reflective material. Altering the angles of the cones would allow redirecting sunlight.
In a way this is a worse plan than solar power satellites because it actually could be used as a weapon. Solar power satellites can simply have fixed focus, and be defocused so that they cover an area instead of targeting a point, and then they cannot be used as weapons at all. The same does not apply to this idea. You could focus it and burn up cities. But it also doesn't involve putting crap into the atmosphere.