I suspect that these hubs are prone to corrosion damage (the sealing etc is very little different from many other IGHs) if used in all weathers but I have not yet seen this in one of these hubs with my own eyes. Other troubles appear rare; remember that the basic internal design is well proven; automatic 2-speed hubs of this sort have been available (on and off) for nearly 50 years. I first rode one of these hubs in about 1971 when I was a nipper; they were not (certainly widely, perhaps at all) sold in the UK at that time but one of my school chums had one on a bike that had been brought back from Germany. It felt very odd indeed then to ride like that and disappointingly my chum seemed reluctant to have his dad take it to bits so he could tell me how it worked....

It is possible that the change of manufacturing plant (was Germany, now Taiwan) may have introduced some anomalies but the basic design is sound.
There are some reports of the shift point not matching the expectations of the rider, which I attribute to poor hub selection in some cases; I am not sure of the current state of affairs but there used to be two distinct models available; one for small-wheeled bikes and one for larger wheeled bikes. In any event the shift-up point is fixed in terms of wheel rpm and this is a different speed pro-rata with wheel size. If the shift point is wrong the only cure is to do something with the shift control spring.
In terms of first use I would adjust the bearings correctly, use the hub a few hundred miles, then regrease before winter comes.
I think it is best to use spoke washers when building on these hubs because the flanges are not very thick.
cheers