Even the best lineups have a #9 hitter.
The question that is worth asking is whether the cost of Reynolds or Happ is worth the gain.
The Crew already has Yelich/McCutcheon/Renfroe/Taylor in the outfield and DH. Personally, I'd promote Turang, and have him rotate a bit between SS/2B/CF, get Hiura up and make him full-time DH, and go with either McCutcheon/Yelich or Yelich/McCutcheon in left/center as appropriate. the Crew could even use Wong in the outfield (he had limited OF time in 2016, and didn't do horribly).
Sometimes, looking in-house (especially the minors) might be the better option.