I did an obstacle at Hollister Hills SRVA with my club called "The Ravine" (or something like that). I think it's a good comparison of how the LX570 flexes compared to the suspensions of other vehicles, including a Bronco Sasquatch that went right before me and a couple built jeeps. My LX is at the 8:47 mark and the Bronco is at the 6:36 mark.
Yeah considering the LX is IFS I thought it did great. All the vehicles were lifting tires, even the built jeeps, so it makes me think the IFS and lack of articulation that comes with it, are not much of a limiting factor when it comes to these types of obstacles. Also it looks like the amount of LX articulation is equal to, if not better, than the Bronco, at least from watching the video.
Interestingly, it's the Bronco 4-door that has longer wheelbase. Pretty sure the LX has the stronger RTI stock (against 4-door Bronco), let alone modded nicely as @supercarrera has done. I agree it's readily apparent in the video that this is the case.
Published RTI only available for the Bronco 2-door. The 4-door adds wheelbase which impairs RTI scores, with exactly the same suspension flex capability of the 2-door, which would mean the LX likely beats the 4-door handily.
Based on the 2-door, it may be possible to roughly compute a theoretical RTI for the 4-door Bronco based on the wheeelbase difference. Ford also provided some potential scores based on a different methodology which if I cross check is not far off.