I think most here on the board would agree that the weak link in the rear differential is not the 3rd member/electric locking diff. itself, but the splines from the full floating shafts.. That's what fails, they'll twist under extreme load/shock, and therefore break and cause a mess in the differential itself resulting in a 3rd member breakage....I do feel that 35's with stock shafts should be fine, as almost everyone on here now is running 35's..There all fine.. Like you mentioned before, the ARB differential is stronger, but the stcok Toyota diff. is plenty strong too...
One word of caution, though: If you're making a home-brew circuit/harness you will need to ensure you don't engage the locker when you're going too fast. The stock harness has safeguards to prevent this.
I posted more on this somewhere. Nothing breaks, it is the long side axle shaft that gets twisted inside the e-locker by the spider gears. Then you can not remove it. Chromo axles are not going to solve this since they normally will allow for more twist before they break.
You do not have to break an axle for this to happen. With large tires >35"'s you might just one day find yourself unable to pull the short side shaft and then you are stuck cutting things apart to remove it.
It should be fine, but no guarantees. I think the most damage comes from the larger diameter tires. However if you are going to use the HP you might have issues as well, but I think you would really have to try.