Alan wore a white dinner jacket on the World Cruise in Jan/Feb along with many other male passengers. Of course we were in the Southern hemisphere (LA to Hong Kong via South Pacific, NZ and Australia). He also wore one on the Panama Canal cruise in early April. He likes his so much I'm sure he'll wear it on the Norway cruise next year if there are formal nights.
I don't think dress codes are as strict these days. I say wear what you like (but I'm no expert ;) )
