DorkyThorpy Blog is comparing gear efficiency and the results are utterly fascinating.

The bigger range of a 7 speed internal seems to be 4% less efficient than a derailleur or 3 speed internal.

But the 3 speed internal has a VERY slim edge over a 27 speed shimano derailleur.

Anyhow see all the number crunching at the link after the jump.

dorkythorpy: Hub Gear Efficiency vs Derailleur Gear Efficiency