Mark, are we talking about the same thing here??
Ok...that shackle does NOT fit flush with the hitch (right?)...it sticks out from the hitch. So, if you're approaching the departure angle of your 4runner, then this thing will hit (may even damage it?). I did NOT say anything about the hitch hitting the ground...i am saying that the long shackle will decrease your departure angle. Anything that adds length to the hitch will decrease departure angle UNNECESSARILY. Now, if you're telling me that you take if off when off-roading, then i am all for it...but, then what is the point of having it then?!
Tow pin...i use it all the time. Actually, i have a Master Hitch Lock and use that pin to hold onto my tow strap. I gotta tell you...i have NOT seen any tow strap being damaged due to using the tow hitch pin and i was only answering 44's question. Also, i do align my tow as much as possible. I carry a 2nd one for length and backup. There is nothing wrong with keeping a close eye on your tow ropes...and trust me, i am not at all worried about the hitch rubbing on the tow rope.
The tow pin (or hitch lock pin) should be plenty strong if you're towing within your load range. Hell, even in YOUR application, you need it to hold your shackle to the hitch! The tow pin is also shallow enough within the hitch to not create enough angle on the hitch box itself to eat up your tow rope. Is there really any data to support using these hitch mounted shackles??????
And like i said above, if you manage to bend the tow pin, then a shackle mounted to hitch VIA TOW PIN would NOT help.
What are you talking about in the 2nd-to-last paragraph?? The tow pin goes thru the hitch...and things attach to it spreads it's weight across the whole hitch. What are you talking about? Are we talking about the same thing here??? And how is mounting your tow rope to the above shackle be any different since you're ALSO using the tow pin to hold the shackle???!!
As for bumper protection from rear-ends, i have no doubt that the shackle helps. People in G-wagens can't drive worth a damn!