I do see your point slightly, however the two i'm talikng about are slightly smaller than the two which you are talking about and they don't look too big for the body which the 2 currents Topfhelms do.
Anyway heres some screens showing the differences and similarities. I hope they can show the differences better than the OP screens and show how cool these helms really are
The Bolzano compared to the Topfhelm
The Greathelm compared to the Rounded Topfhelm
*Note* the Bolzano and Topfhelms have been lightened so you can see them more detailed, I think they look better like that too