Ok, I had it examined by my gf who - unlike me - happens to have some real knowledge on the topic, and she actually told me "Tettigonia Viridissima" as well (she does not know of this thread, so that makes me fairly confident that's the one). She's saying that subtle differences are possible (in case of sub-species) but very unlikely. She does not know if there are subspecies of the Tettigonia Viridissima.

I, personally, woundn't really know. The wikipedia pics are from the top, and the angle is too different for someone like me knowing nothing about insects to tell.