the Hollinger is a very very good box. I have visited the factory and seen the box in question and the parts that go into it. it has some massive bearings in it, probably twice the size of the ZF boxes. the crown wheel and the differential are all cnc machined out of a single solid billet, so if you want to change the ratio you change the diff centre carrier as well. all their steel comes out of Germany from about 2 mills as they have been the only ones capable of meeting the quality required. Its all barcoded and they can trace each gear back to a particular billet. The casings are a double wall casting next to the pinion shaft support all to provide maximum stiffness and light weight. The box comes with a cooler pump installed internally as well.
take not of the rating, its something like 800Nm under race conditions for continuous 24hr period. they don't rate it by HP as that is not what gear boxes do, they transfer torque. you could have something that does very little work (power) yet transfers a huge amount of torque. they are not directly relatable. Hp is a product of torque, however torque is not a product of HP
Ryan