The XLR is simply a high gross weight version of the 321NEO with a custom aux tank in lieu of the optional modular center tanks and modified flaps for improved single engine takeoff performance.

Otherwise, it's the same wing as the rest of the 320 family except for internal structural differences common with the other 321s.

So, no, it's not a .81 airplane and the initial cruise altitude at those high weights will be shockingly low. It would otherwise cause chaos on the tracks with its long range cruise speed, except it will be flying below everything else for most of the profile.