This widespread perception about metal tweeters is crap and has taken on the status of audiophile myth along with direct drive turntables and MM cartridges. Metal dome smoothness depends on how the dome is damped among other things. I have a low tolerance to harsh treble, but my Mirages have a treble that's sweet as silk--powered by titanium domes. They use a cloth suspension to damp the tweeter and it works. Because of the light diaphragm and titanium's resistance to breakup, the titanium tweeter is both articulate and very smooth with no artificial high treble boost or edginess.
That said, there are lots of great fabric tweeters as well. It seems the Nola Boxer would be a great choice for the OP's criteria. Also, GoldenEar DOES make a pair of monitors, the AON 2 and 3, which are stand-mounted and use a most excellent Heil-inspired folded ribbon tweeter.
That said, there are lots of great fabric tweeters as well. It seems the Nola Boxer would be a great choice for the OP's criteria. Also, GoldenEar DOES make a pair of monitors, the AON 2 and 3, which are stand-mounted and use a most excellent Heil-inspired folded ribbon tweeter.