Meh, they don't necessarily need a boost, but I think they do at least need balancing between the two. If one is better in all ways except armor (where it's inferior) and speed (where it's equal), yet isn't a fair bit more expensive than the other (much less less expensive, which you've already said needs to be fixed), then I think that's a bit of a problem.
Assuming about equal price, and if you don't want to give the Yacht more GB turrets, I think it could use more cargo (2000, or 2500 like the Kusari version). The much greater armor of the Yacht is balanced by the Kusari ship's much greater maneuverability. Increasing the Yacht's power core so it could fire a heavy GB turret (even slowly) might help, and would be balanced by the Kusari ship's greater anti-fighter capability (more transport turrets). The dual-CM on the Yacht might warrant a somewhat higher price, but not anything insane.
CDs are optional. They're nice to have, but not necessarily necessary.
