When David and I first sought bids, we spec’ed a metal roof. Everyone told us it would be too expensive. We picked our contractor, we accepted asphalt shingle, we moved on.
Today, David talked to the contractor, and he told us he’s going metal. Because of the low pitch (2:12), he didn’t feel confident about the protection from leaks that asphalt shingle would provide. He is going to use sheet metal instead, standing seam.
I’m so excited! I know it is a little thing, but I really wanted a metal roof for so many reasons. They are durable, attractive, and energy efficient (they are even eligible for certain tax breaks):

Mill-finish metal roof systems have very high solar reflectance, providing further reductions in heat gain. Metal roofs with oven-cured, pre-painted organic coatings that incorporate new “cool pigment” technology offer high total solar reflectance and high infrared emittance even with darker colors. Emissivity as high as 90% can be achieved for painted and granular-coated roofing. Such pre-painted metal roofing products meet the reflectance requirements of all major energy code initiatives. Finally, unlike many roofing materials, metal’s low thermal mass will not store heat and radiate it into a building in the evening hours. Painted metal roofs retain 95% of their initial reflectance and emittance over time.

From Cool Metal Roofing by the Cool Metal Roofing Coalition