Has anyone removed tarnish from Gallo tweeter?

Just checked the (growing) blotches on mine. They don't look a thing like fingerprints. The tweeters will be uniformly brown before long, just like the color of my Due's. Dave

I've had mine for probably about a year now, and they definitely show the fingerprints. My guess is that the oils transmitted through the hands accelerates the tarnishing so that the fingerprints show up first. Over time, I'm hoping they become more uniform, but as long as it doesn't impact the sound (doesn't seem to), I'm fine with it. Just one of the quirks of a very unique speaker.

SO, the big questions: is there any reason to believe this tarnish/patina thing affects the performance or longevity of these tweeters?

Not according to Gallo, Joebone. It happens to all the CDT tweeters in due time.