Pugilistic Animus
[QUOTE] The heavier plane at glide speed will reach the same position as a lighter plane, only faster...if a made an error don't crucify me 
[ /QUOTE]
Correct if you fly with (L/D)max speed (=GD) for any weight.
Otherwise, if you fly faster but same speed for any weight, the heavier has more range.
So... I want more range so I am going to add a few tons to my Cessna 140 or Piper cub, and that will give me intercontinental range? Excellent.
For a descent with idle thrust (residual) the greatest range will occur when the aircraft as a system is operated at the tangent to the L v D curve which is LD MAX. For a heavier aircraft, the speed will be greater, and sink as well as velocity will be greater, range itself doesn't increase.
Lets put this to bed, again,
It is a little protracted but is simpler using the FTM-108 Ch 8 reference than many others.
Gliders will have greater speed when heavier, they don't go further just because of speed for heavier weights, but that changes when wind effects arise, where having a higher IAS for best L/D may be helpful, in headwinds etc.