I had three or four Collector Rifles/Shotguns in my day. They all got shot - now all are sold. I didn't sell them for profit - but just because technology naturally increases & better guns are on the market every few years.
A limited edition of those Black Diamonds were made. He could put it up for auction at gunbroker.com (or) auctionarms.com..... he may get an extra $150 for it tops. If he doesn't like a bolt-action ML, then I would try it myself... then take that "hard-to-sell" but "possible" $480 & invest in a nice Encore or Omega. I would suggest waiting for an about-to-be-releasednew-model T/C Triumph that will hit the stores around June 1st, but I never recommend buying new model rifles - until they have been on the market shelves forover one year.
Let other buyers deal with "getiing the bugs out".