I'll borrow this pic of a Manners light fill. The fill material (the white colored fill) used in the Edge and in Manner's lighter stocks is not as solid as that in standard fills. Manners acknowledges this and at least uses the more solid, durable fill in critical areas (the gray colored fill material).
I found a bubble in the paint of my most recent edge. After I removed the paint I didn't like what I found. I made several calls to men who bed these stocks day in and day out and found out that this was not unusual and the reason they all preferred standard fill.
Manners with standard fill in critical areas:
My last Edge, around the rear action screw pillar. I believe Manners is using their heavy fill behind the rear action screw, the same place where I have a void. It doesn't give me a warm fuzzy feeling.