LLC on vs off is just a voltage adjustment, it (obviously) does not change the vrm circuitry. Whenever going from similar heavy load to light load (LLC on or off), there will be similar magnitude overshoots as the same relatively cheap vrm circuitry (on motherboards) can not make perfect and fast enough adjustments from same load (and no one is going to want to pay for an expensive solution where minimal vdroop/vdrop is needed to prevent overshoots).
Suppose you need 1.36 load to be stable, and 1.38 in bios with LLC on or 1.43 LLC off gets you there. Since your load is same, and your going through the same circuitry and recovering from same load, your overshoots should be approximately same magnitude.
Also, remember, overshoots are proportional to voltage, so higher vcore = higher overshoots. While some tolerance is no doubt built in, and an expensive mobo with better vrm circuitry will have more leeway, once you get too high in vcore, even with LLC off, overshoots will be higher than what you set in bios. The vdroop and vdrop level was to protect from overshoots at near stock vcore (with some tolerance built in), so again, once you get much higher vcore, overshoots at some point will be above bios setting regardless of LLC setting...and no one knows tolerance settings except mobo manufacturer.
In other words, you are overclocking, so you are already out of spec. And while you shouldnt fool yourself with LLC on, you also shouldnt fool yourself with LLC off.
Not trying to tell you to use LLC or not, especially since I dont see that much of a difference between two, other than you idle lower with it on, and for some reason, large vdroop/vdrop is annoying to me. My preference is the GB solution of simply reducing vdroop/vdrop to a low level, vs eliminating it, since I know I am out of spec with it on or off at my vcore anyways, and a small amount for whatever irrational reason is less annoying to me. And since most degradation occurs at load vcore + corresponding overshoots from given load with given circuitry, according to those that manufacture them...then I doubt it matters one iota whether you use LLC or not, what matters is how high your load vcore is and how good your vrm circuity, and how lucky were you with your particular cpu's quality on how it will resist degradation.