I have never felt like I could use an extra 1/2" of sidewall when off road, honestly. It's not like I run up and down the Rubicon every other day either, though. For me, picking the 285/60s was simply a matter of convenience and practicality. I don't have a roof rack or rear bumper mount to carry a full size spare around - nor do I much want to or, even worse, put this giant donut in the trunk - so the largest size I could realistically fit under the car (partially deflated) is a tire that's 31.5" in diameter or less, which kind of limited me to 285/60 or 265/65 over an 18" wheel. Also, I don't want to travel around with a permanent lift or modify my car in any way to fit larger tires - the LR4 is my daily driver, I use it for business and occasionally as a family hauler. I'll use my Llams when wheeling to lift myself another 3 or 5 cm, but normally I am at standard height, which is no problem with my size tires. No rubbing anywhere, except very, very slightly under extreme compression or at full steering lock.
On the road, I feel I gave very little away in terms of handling or comfort by staying under 32" in diameter with a relatively stiff compound and not overly aggressive tread like these LT Nittos. However I have never tried anything larger on my LR4 (or my former 2006 RRS), and I don't know how the car would do with a larger tire, so I'm afraid I can't be of much help in your decision. Good luck!