As far as I know this is the first time this particular panhard/track bar relocation bracket has been discussed in the 5th gen section. I'm intrigued.
I understand the concerns over messing with suspension geometry, that's inherent, but I also know from first hand experience that this kind of mod is common in the Jeep world, especially with the JK's.
Jeeper's also often lift their vehicles much higher than the typical 4Runner owner though. That said, from my experience, Jeep's also tolerate lifts less favorably than Toyotas. For instance, my 80 series Land Cruiser came factory with what Jeeper's refer to as "high-steer', with the front track bar and tie rod mounted above the steering arm, instead of below. I lifted my solid axle cruiser over 4" without messing with the steering links at all, whereas my JK required numerous "high-steer" modifications at just 3" of lift to eliminate bump steer and death wobble. Toyota does a pretty good job of engineering their suspension, even at stock form.
Regardless, I don't see need for a rear track bar relocation on a modern 4Runner if you're keeping it at what can be considered "standard" lift heights of 2-3 inches. This begs the question, are you experiencing any negative handling issues? I'm really just interested to learn why you're considering this mod. Then again, if you're a new Toyota owner coming from a Jeep, I can understand why you might think this is a necessary mod, no offense intended, I've just been there myself.
My 4Runner is resting at over 4" of rear lift unloaded, and I don't notice any concerning handling issues. I do have an adjustable rear track bar installed to re-center my axle.
That said, I would be interested to see how this works out on 4Runners running higher rear lifts. Tempted to try it myself, I just haven't experienced any negative handling characteristics that would justify the cost and time of this mod.
No angles, but for quick reference here's my rear panhard, again at over 4" of rear lift, nothing to be concerned at in my experience.
If you do install this please report back on your experience, I'm sure I'm not the only one who's curious. Thanks!