It's worth noting that the heavier glider has more energy
stored kinetically and potentially. Whatever the difference
in height is, it's due to drag, and heavier glider needs to
give up less altitude for any given amount of energy
required to overcome drag.

Since Newton was hit by the apple, it is very unfortunate that everywhere on
this universe, any system trying to carry a load away from the center of the
planet will have to work harder than one travelling light. This is intuitive
enough. I wonder what is catching here. For any ten feet of height, the
heavy system will have to work more than the light system. True, our
ballasted glider has more money in the bank at the start, but it will have
to spend more on the way up. I hope that money comparaison will help. There
is no way around this fact. Travelling towards the center of the planet is
another ball game. The reason that for a given angle of glide, the heavy
will go faster is that the weight being larger, it's component parrallel to
the direction of travel is bigger. That simple. This is the motor. Drag is
"induced". it is not running the show.!!
Hope this help.
Bravo Quebec