Boy did that snow work some majik on me last night, I slept the best part of the morning away. JD, I am actually having problems with the extra thick fillered edges myself right now, amongst other things. Since I am machine sewing, and therein lies most of my problems, you are perhaps doing things a bit different. Just a couple of thoughts, cut your insert just a hair wider than necessary and install that tiny bit extra as overhang. If you are having trouble with keeping it even then cheat slightly and let it be the part that protrudes. If you desire fillers then avoid thin ones, they twist and roll on you to much while working and sewing. Do not just look at it flat, turn it up and sight along the edges as you hold them into alignment, especially at the toe and mouth bends. That bit of slight protrusion on the filler is ok BUT you must try try to keep the top and bottom edges of the main body even at the spot where the liner stitching and main seam stitch will meet....(even use a light pencil mark on the edges to help lighn up those stitch marks if necessary. I use strong spring clamps on the main seam while the glue sets, keep the leather seam area dry and the clamp jaws padded. After the glue sets I go to the sander to dress the main seam down but try to do it with ight strokes and keep away from the starting points of the existing liner stitching as it is already at the proper distance from the edge and you went to extra trouble to keep those two important spots on the fillered edge just right, right? I do a light pass on the sander face up and then flip it over and do another light pass with the holster face down, repeating until I have a nice even edge and shaped the way I want it. Even with these light strokes you are miles ahead of the guys working it by hand with sanding sponges plus you are not unnecessarily bulging the leather with pressure. Now is when I like to edge those corners and go back over it with a warn out sanding sponge. If everything has remained really lose on those all important stitch meeting points at the top and bottom of the mainseam then your stitch groover should be able to meet at them with the previous setting. All the rest of that mainseam can be done as a free flowing process, within the bounds of your pattern, because the groover simply follows them. This should leave very little space for the need of filing with wax.