Spoke breakage is usually not the result of the style or size of spokes, but the result of an incorrectly built or tensioned wheel. Lighter spokes, especially 'butted' spokes can actually be built into a stronger wheel because the added flex through the centre of the spoke takes some of the stress away from the elbows (where breakage normally occurs).

I have been up close to 300 lbs in the past and use standard 14 ga. spokes and do not have a problem with spoke breakage.