That choice is mostly personal preference. If you plan to keep it, do you mind if it is not 'minty fresh'? In todays market, I don't how how easily you could turn it around with hopes of much if any profit after putting $350 into it being refinished. However two of the most knowledgable McDermott collectors have already posted on this thread, and they know the McDermott market. (Phinmole and Rodcar)
Personally I have about 7 older Mcdermotts, mostly D series. One i have had re-finished, but I had the butt plate and joint collar replaced anyway as the collar was cracked and the plate was engraved. I have heard that the new finish they have won't stick to older butt plates, but i havent personally confirmed it with Jayme Cernika (CS manager).
Unless the cue is heavily damaged, I look at a cues bumps, scrapes and nicks as character. Each one probobly has a story.