A lot depends on how large of a tire (and it's weight) you go to. The larger and heavier it is you may need to go down in gearing to recover the shift in your powerband.
As far as ABS, I have not heard of any difference in performance. Keep in mind though the heavier the tire, the more inertia it has, and the harder it is to stop.
ESP (
), I have had repeated issues with the lift, and tires on my 06. Though things have clmed down since the alignment. I think this falls in line with most others who have ESP and a lift/tires. It only kciks in occasionaly now, and it's a rare annoyance, not dangerous (IMHO).
Speedo adjustment isn't needed with 245/75's form my experience, and 265/75's is only off by a few % at highway speed. It's easy to perform eith a reflash at the delaership, you just need to know the true diameter, or revolutions of the new tire.