What's the history?
I have several guns with white line spacers.
They are 70's vintage and look correct. I wouldn't think of removing them. Of course, I'd never add one or use a replacement pad that had one unless on the proper vintage piece.
In fact, I recently refinished a 1975 Marlin stock that had a nice piece of walnut under that unfortunate Mar-Shield lacquer. It took some judicious working with fine abrasives to make the edges of the spacers white again. The stock looks great with Varathane 'natural' stain under a wiping poly. It would look wrong without the white trim.
So, who was the trendsetter with the white spacers? Weatherby? 1950's? 1960's?