Well, with respect, I have to say that I would have had the helmet polished.
I know there are different schools of thought on this issue, but in my view I think the helmets should be displayed as close as possible to the condition they would have been in when they were on the parade ground. Picklehaubes ala 1895 were meant to be dazzling. So I will gently polish (taking care not to touch original gilt etc.) the metal fittings periodically. Maybe once every 5 years or so.
That's just my personal perspective. "Suum Cuique"