If you want a super stiff crank, and very light. the Cannondale Hollowgram SL is the way to go. I would have purchased those, but my BB is a 68mm BSA english thread. For me to use the Cannondale, I would have to purchase a special spindle that converts the 68mm to use the BB30. Went w/ my second choice, which is probably just as stiff, just a bit heavier, the Rotor 3D 2x9 Cranks.
Good luck,
Kevin