How much can weighoff help grand action playability? Sometimes, as with poor action geometry, weighoff will not help unless problems are corrected first.
I recently I found myself so challenged by a vintage Baldwin L. The hammers, shanks, and whippens had been replaced and were in good shape. But the action did not play well. My customer wanted to know what could be done for her attractive instrument that played like a truck and no longer held its tuning. I recommended the fairly expensive route of new belly, block, and strings, plus deep regulation, which she agreed to.
We weighoff a key to help its note function properly. With good geometry, good regulation, and appropriate friction in place, key balancing fine tunes how well a note will play. Key weights, traditionally made of lead, offset weight and friction on the back side of the balancerail to aid the player make music from the front side.