I made an electric guitar a couple years ago that is all good except, by the luck of the draw, the neck geometry is such that the truss rod needs to be nearly slack to get good relief. The rod is a double action style from LMI with a rectangular steel bar on top (against the FB), rotating rod below. It has shrink tubing over the rotating rod.
There are 2 problems with the slack-ish rod. Most annoying is the rod has sympathetic vibration with the strings which causes strange wolf notes. If I tighten the rod, this goes away, but then it is a buzz-feast with the strings almost on the frets and negative relief. The second issue is that you can hit the back of the neck and it rattles in the slot.
its bad.
The owner is ready for me to fix it, and I've got a couple path's forward that both involve removing the FB. Removing the FB is not trivial since this instrument has some elaborate inlays, but I will deal with that.
Solution 1: Remove the FB, and simply re-glue it with induced relief so that the rod has to be tightened significantly to bring the board flat.
Solution 2: Replace the truss rod with a single action compression rod that is in a tight slot (which I should have done originally

I strongly prefer replacing the rod with a good compression rod. However, this is significantly more work, and because of the headstock I may need to change the adjustment location to inside the neck PUP cavity. I'm not afraid of filling the existing slot and re-routing for the smaller rod, all the woodwork is no issue, but I'm wondering if it is worth it. Also, the owner has read somewhere that compression rods are bad for tone

Advise is welcome, opinions will be tolerated.