The difference in height will be negligible.

The glider's energy, both potential & kinetic is proportional
to Mass so the height gain for a given loss of velocity
will be the same.

However the ballasted glider will have a better sink
rate at 100kts than the unballasted one so during the
few seconds of the pull-up it will 'lose' less height.

On the other side of the equation the un-ballasted
glider will be able to pull up to a lower speed, so
it's change in velocity will be greater so the resulting
height gain may be more.

(My money - if I had any - would be on the un-ballasted
one)