As many said, if you decide to sand and remove the filler, you might find an ugly wood finish. But you can always do like Fender did on my MIM: just glue a veneer of a nice looking wood on both sides. You can even buy a quilted maple or flamed maple veneer of 1mm thick. I assume this is how Sire does its finishes and still remains price competitive. And to avoid the ugly looking on the sides of the instrument, simply tint them with a dark color.
