You can improve your stocker a bit by going to a 30" tyre - you lose some articulation doing it without a lift, but you gain some clearance under the axles. It's a trade-off.
As far as "rollover risk" - given a properly designed vehicle, that's more a function of the driver than of the vehicle - and a skilled driver can compensate (I used to play bumper tag with a boss years ago. He drove his 30th Anniv Camaro, I in my 1987XJ 3"/31's. At no time did any of my tyres leave the pavement, nor did I break traction, and I did some truly inspired driving to keep up with him...) As long as you don't get stupid with your driving, you'll be fine.
If they keep harping on "rollover risk," know this - I once saw a man roll over a Corvette on a winding road - even a low-slung road car isn't immune. I was walking down the side of the road, he blew past me, and rolled over right in front of me on the next turn.
I couldn't help myself - before I did anything, I crouched down and said, "I bet you feel really stupid right about now..." Called in the SVA, figured the car would be totalled (it was,) and reported unknown injuries (turned out there was some slight internal bleeding from blunt impact, but nothing that was life-threatening on scene. No grievous ruptures - some bruised organs and a bit of "weeping" of blood on the inside.)
3" and 31's is a good combination for the XJ - and if you're going to spend time on the trails and such, your "road kit" will help ballast you anyhow. You get into rollover territory when the centre of gravity (CoG) of your rig gets outside of your "footprint" (rectangle bounded by the contact patches of your four tyres) - keeping your weight (vertically) low in the vehicle helps keep your CoG low (reducing rollover risk,) and keeping all four tyres on the ground and not getting too far off-camber will keep your CoG inside your footprint (reducing rollover risk.) You keep all four tyres on the ground by not trying to zip around corners and such, not hitting bumps at speed, and obvious stuff like that. The only time you're probably going to get off-camber enough for it to be a problem would be if you were to get into 'technical crawling,' at which point you're pretty much required to have a roll cage anyhow. And you'd be travelling at very low speeds (10mph or less.)
(that'd be me), married with 4 adult kids who has his Jeep lifted 3.5" with 11.5" wide tires". It's the best of my vehicles. I know every corner of it, it's just a hobby for me. The width of the tires offsets the height of the lift. Higher lift, wider stance. 
