Actually, I'm looking at my SSE Manual right now and it says NOT to sand the parts. Here's the paragraph:

IMPORTANT: The laser cut parts contained in the kit are extremely accurate in outline and fit. They are meant to be used directly out of their sheets, without any trimming or sanding unless specifically called for in the instructions. The Laser cutting process produces a brownish edge to the parts and, in some cases, a blackout edge may result when cutting harder plywood parts. CA adhesives work perfectly on these parts and they do not need to be sanded to remove the discolored edges. In fact, sanding the edges of laser cut parts can change their shape and/or dimensions, resulting in a poor fit. DO NOT edge sand the laser cut parts in this kit.

For me, I trust the experience here at RCU. If Ken and Bruce both suggest lightly sanding the joint then so be it. I think the key is not changing the shape. Furthermore, I wonder if the Sig advice is based on using CA and not wood glue?

MA