I suppose I will chime in on the subject. This is mine:
Stock narrow Dana 30 front housing. Stock AMC 20 rear housing. Stock gearing.
Front has a lunchbox locker and CHROMOLY axles. Chromoly is the key point here. Front also has Warn premium hubs, and Stage 8 hub bolts.
Rear 20 also has chromoly 1 piece axles, and welded gears to lock it. I also welded the axle tubes on the 20 so they can't spin.
Cast iron diff covers (I have Riddlers) or even chromoly ones (like from Crane) will strengthen up the diffs a bit in theory, at the very least protect them better.
That being said, I run 35" BFG Krawlers. I wheel this piss outta this thing on 5+ trails all day long. It just works very well for what it is at the moment, and knock on wood, I have not broken yet. And I follow the super custom buggys on tons, and watch them break as I crawl on by. I am sure my luck will run out, which is why I plan on upgrading to tons in the future, but that will take a lot of $$$.
The biggest thing is how you use the skinny pedal. Don't let the tires bind up, and when they start to, STOP. Pick another line. I am amazed the obstacles I have wheeled through with my set-up. Right now, I am just limited by flex, and I can make it through most things the way it is. But I am either going SOA or linked in the future, and when I change that, I will go with beefier axles.