I also have to disagree with Peter C. Most civilian pipe bands I have seen have chosen to have their kilts pleated to stripe. It is not just a military style. Same is true of non-pipers. Pleating to stripe is in every way acceptable for civilian kilts, pipers or not.

However, that being said, I also know of plenty of pipe bands who have their kilts pleated to the sett. It all just seems to boil down to what kind of look the pipe band wants to have.