Found a biker physicist blog and came across this little gem, basically it says for the amount of energy needed to spin up and maintain speed with lighter vs heavier wheels it makes little difference overall (except to your pocket).
The total mass of a light rider (60 kg) plus bike (8kg) plus associated gear like helmets and water bottles (2 kg) is roughly 70 kg. Of that mass, the wheels (including tires and tubes) account for roughly 2 kg of that number. The total kinetic energy of a cyclist is therefore:
KEtotal = KEwheels + KE bike =
Where v is the linear velocity, I is the moment of inertia and r is the radius of the wheels. Now let's say that we're moving at 10 m/s (36 km/hr).
KE wheels = (100 J + 20 J) = 120 J.
KE bike = 3400 J.
So you can see that the wheels account for about 3% of the total kinetic energy of a cyclist. The rest, 97%, is dedicated to overcoming the inertia of you and the rest of your gear. Therefore, a large change in your wheels is going to have a relatively small effect. However, a moderate change in body mass is going to have a huge effect. That said, small changes can add up to big ones.
My point is that changing your wheels will not dramatically change how fast you go. It will make a small, but significant change. You should also beware anyone who tells you that brand X wheels give you a 3 km/hr advantage. They probably don't. As shown above, a 10% change in wheels gives less than 1% change in total mass and kinetic energy.
The full text is on here: http://www.bikephysics.com/paper.htm#analysis