Berlin is absolutely not the right map for this vehicle, although there is one spot that might work for it - overlooking one of the two long flat roads leading to A, where no gun depression is required and you can hide behind solid rubble for cover.
You should think about it as a Dicker that fights on flat ground instead of hilly ground. Abandoned Factory, Cargo Port, Breslau, Sands of Sinai to a degree if you’re careful with positioning, Seversk, these are all maps where the Hummel can work very well.
Both of these have been changed only recently, and the reload buff in particular is precisely because TDs have issues across the board. Just look at the M10’s reload speed. I wouldn’t be surprised if the Hummel got reload buff eventually just like most other mid tier SPGs.
I love these people’s (gaijin) double standards when they decree that the BR/OF-471 does not even need to penetrate in order to destroy a Panther/Tiger but when the situation is reversed & you manage to hit an unsuspecting 45 mm inadequate tin can with substandard armor (T-34) with TWO 150 mm Gr.36 rounds, not only does the thing withstand it, it then immediately proceeds to one shot you as if nothing happened…
