Well, i have some experience...my brother has the Lexus LX470 and i have an '02 4runner (with plenty of experience with the new 4th gen 4runner).
Here are the major points: TLC vs. 4runner
1. 4runner is lighter with same engine = better performance and handling, esp. with XREAS.
2. 4runner has all the latest technos (Hill Assist and Downhill Assist). Torsen center diff is slightly more advance than TLC's gear-based center diff. They are same in design but Torsen is more flexible on-road because it can vary it's torque distribution based on traction. In off-roading, both system are equal.
3. TLC has better approach, breakover, and departure angles.
4. TLC has more ground clearance.
5. TLC's underbody is very clean...very little protrudes down there to snag a rock. It is much cleaner than 4runner/GX470 & Sequoia. The fuel tank is tuck up high into the body (unlike it's Toyota siblings). The whole bottom end in front is covered up by a plastic skidplate. The front skidplate is steel. It is quite impressive organization, given the room inside the TLC.
6. The frame of the TLC is probably stronger. Back in 1998, when TLC was first introduced, Toyota claimed that it's frame was the strongest of ANY production SUV in the world. They aimed to match the Range Rover...they surpassed it's frame strength.
7. The suspension system on the TLC is superior in off-roading. Despite torsion bar in front, the whole suspension has a lot more travel than 4runner/GX. Up to today, TLC still holds the record for the highest RTI of any vehicle with independent suspension. It even beat out Jeep Grand Cherokee, who has solid axles in front and rear. It loses only to Land Rover Discovery.
(RTI: ramp travel index. You run a car up a certain degree ramp, usually 20 degree. You measure how much a vehicle can go up until the one of the rear wheel loses contact with the ground.)
8. The rack-and-pinion steering on the TLC is specially designed to fit high up into the body...to avoid damage in off-roading. This has been somewhat of a problem with 4runners (and GX) in off-roading. The steering mechanism in the 4runner hangs low...most SUVs with rack & pinion steering hangs low due to design constraints. I believe that the Range Rover's system is also up high into the body (like TLC). That is why hard-core off-roaders still prefer recirculating-ball steering because it can be mounted high.
9. According to a site (forgot exact address), the TLC is able to climb 45 degree hill and cross a side slope of 45 degree. That is 100% grade and 100% side slope capability!! Only a handful of SUVs on the planet can do this. The new 4runner/GX can do about 42 and 41 degrees. This capability requires good vehicle design (wheelbase, length, track, etc.). In addition, the oil pan and engine must be able to work at those extreme degrees.
Conclusion: If I were to have a choice in off-roading, then i would pick the TLC...proven chasis, proven suspension, and proven heritage. Remember, back in 1998, Toyota made the TLC with no limitations on budget...it was their best effort after many years of research (over 5 years i believe). Let's just say that Toyota spent a lot of $$$$ on the TLC. That is why TLC/LX470 is still regarded so highly after so many years and arrivals of so many new competitors.
My opinion.