I've noticed the same. Against a H16, it varies... sometimes I'm able to pass them left and right, sometimes they just seem to have an advantage. I think their lighter weight and thinner profile makes them easier to move in the water, but our larger sail area can give us the advantage once we get going. H17's seem untouchable in light air (but they're also a lighter boat and sail singlehanded), though I've never raced against one in heavier winds. The guys that sail them are also undoubtedly some of the best cat sailors out there (I'm looking at you, mbounds!
)
For light wind strategy, getting the transoms out of the water is huge. Get your weight as far forward as you have to! Just get the sterns up! Diamond wires as tight as you can get them. Aside from that, I can never figure out what the best angle is, and usually light means inconsistent, so reading the wind on the water becomes really critical. Downwind, again, I try to stay as forward as possible (crew on one bow, skipper on the other... I steer with my toes
) If the boat is rocking and shaking the wind out of your sails, have the crew pull the boom down to keep pressure on it, keep it open and steady, and hand hold the jib. Daggers halfway up.
As I understand it, mast rake further forward is supposedly better in light air, as it gives you a taller profile, though it moves the sail CE forward and reduces pointing ability. I haven't experimented too much with that.
Any other suggestions I'm missing?