Originally Posted by
seibaatgung
Why, relative to a front dynamo hub?
The AG was a three speed internal gear hub with a dynamo. The FG was a four speed internal gear hub with a dynamo. They had a limited range and generally didn't allow you to set the gearing up low enough to climb steeper hills. If you could set the front chainring and sprocket up to have low enough gears to spin up a hill you would have a very low top gear for on the flat. Also as they are now very old internal gear hubs I wouldn't like to stand on the pedals when riding one as the additional torque generated may result in the pawls in the hub slipping.
A modern front dynamo hub allows you to use any gearing you like. If you have a modern internal gear hub you can probably get the gearing low enough for climbing and have a reasonable flat cruising gear. Modern internal gear hubs probably have a lower minimum front chainring to rear sprocket ratio as well. If you run derailleur gears you can run as low a gears as you like.