I don't lie when I say that portal axles are the best possible thing for serious off-roading.
On the Unimog, they provide a double advantage: An instant ground clearance increase of 20cm or more, and increased of robustness to an already very robust drivetrain. Because the gears in each wheel hub work as reduction gears, there is a lot less reduction that needs to happen in the centre differential gears. As a bonus, the size of the centra differential "bulge" on the Mog is consequently smaller than many 4x4s, affording further ground clearance!
I have never found any evidence of anybody ever having broken side shafts on a Unimog. What I have seen, are unimogs dragging themselves, plus a 10 ton load of timber, through deep mud with only one or two wheels having traction, with difflock on, all day long.
Are there downsides?
Several, of course!
First of all, each hub now also needs to be checked and filled with oil. A common fault on Unimogs is a leaking hub seal going undetected (because it leaks INTO the axle shaft, not to the outside), draining itself from oil, and self-destructing. If you go on a trip with me, you'll see me under my unimog at least once a day checking my hub oil levels
Secondly, these axles do not like speed, plain and simple.
Sustained speed over 90km/h are just not what they are made for.
Luckily, in my case, my 1960s diesel engine and gear ratios make that impossible in anyway, but I think this was done for a reason by the engineers at Benz.
Thirdly, as mentioned in this thread, you have much more unsprung mass.
Great for preventing tip-overs off-road.
TERRIBLE for on-road comfort.
I once drove over some stupid unmarked speedbump on a main road at 60km/h with my unimog almost 2 years ago.
I'm still recovering from post-traumatic stress disorder.
A virtually indestructible drive train with portal axles is the reason why I got a unimog in the first place.
I'm sure a well-modified civilian 4x4 with portals is equally epic off-road.
But all of the down sides will still apply, and it would be VERY costly, so I would think twice.
Portals for sure kill any chance of good on-road behaviour.