Al,

weight in the wheels makes more of a difference than any place else. As you climb you are carrying that weight up the hill, lighter is better. As you pedal you are constantly changing speed in the wheels, the lower mass will make the bike respond easier to the changes. This will give you the perception of more responsiveness in the bike and that will give you the mental push to go faster up the hill. Hill climbing has a huge mental aspect to it. When the bike responds faster, you feel rewarded for your effort and you put more effort in.