I would invite all who claim that key length has nothing to do with
action "feel" to go out to a playground and wag a long teeter-totter up
and down, and then, if you can find it, a short one.  The long one,
because of inertial mass, will have a "clumsier" feeling: harder to
motivate, and especially to get to reverse direction (the equivalent of
"repetition" in a piano).  This is a fact of physical laws that there
is no getting around, unless you are some sort of mystic who can
nullify the normal operational structure of the cosmos.

Does this mean that longer-key pianos must be unpleasant to play?
Nope.  But more attention needs to be paid to their design and
adjustment to make them feel adequately responsive.  Concert Grand
actions, just because they are in larger, louder, and more costly, are
not by nature better.  Indeed, their larger key length is an
unfortunate requirement of getting the hammer-strike point to the
proper fraction of string length, to damp unpleasant harmonics, and is
not a benefit, I have found as a professional pianist.

Again, I recommend that anyone seriously interested in this matter
investigate the work of David Stanwood of Connecticut, who is regarded
almost universally as the #1 expert on resolving action design issues,
and improving factory actions in ways that are demonstrably
quantifiable.  I have discussed the matter of extended reproducer keys
with him personally, and he has working experience in improving the
function of the actions in which they reside.

Gordon Lee Stelter