KDSS allows a very stiff sway bar for on-road driving without compromising off-road articulation. It's essentially a fully automatic sway bar disconnect.
I had KDSS on my '16 4Runner Trail Edition and do not have it on my '23 4Runner TRD Pro. The KDSS did, indeed, improve on road handling. Much flatter cornering, so the '16 really did drive well on the back roads. The ride down cracked and potholed highways/interstates was considerably worse on the KDSS equipped model, though. If one side of the road was beat up, that impact transferred through the back of the vehicle a lot more than it does on my Pro. I realize part of this is due to solid rear axle, but the high dollar suspension on the Pro seems to do a much better job isolating those impacts. Anecdotally, a friend of mine that went from a '14 4Runner SR5 (no KDSS) to a '22 4Runner TRD Off Road (with KDSS) has complained that the ride feels a lot rougher in his TRD OR despite the shocks and springs supposedly being identical to his old SR5. For the average person on a road test, I think the Pro has a noticeably better ride even if it does lean over during hard corner.
I think high quality shock / spring combo with KDSS could be a really great suspension, but I also think that most people don't hustle a 4800lb SUV down WV backroads like I do. Maybe for the typical GX buyer, a high quality adaptive suspension is a better way to approach it. Leave the eKDSS to the trims that will appreciate it.
