I'm skeptical of that.
While the GX has larger running gear, its fuel efficiency and range are abysmal, only the Overtrail comes with a rear locker, but the Overtrail's payload is
reportedly only 1235 lbs, which would be
less than LC250's (though I haven't seen official technical specifications).
Also, in the 550, Toyota is once again force feeding needless luxury to the US market; just as with the 200 and the LX600, in order to get the heavier duty running gear, one must buy tens of thousands of dollars of needless luxury bits; sad.