Yes, the new diffs are junk, compared to the old ones. FYI: the older versions of Xterra/Frontiers didn't have differential issues; they had front CV shaft issues, as in they broke easily. BUT, that's fairly common for any IFS rig that gets wheeled.

You're dead-on when you complained about more HP, but yet smaller front AND rear diffs. Nissan made a poor choice on this, IMO.

As to the Titan, their rear diff is laughed at in the Full-Size truck circles, because frankly, a Dana 44 rear axle is great on a smaller rig w/ up to 31" tires. 33" and above and you're asking to break something on a D44 rear. Period.