I've played the the notion to swap out the drivers and tweeters of my Ti M80's, but then I listen to them, and remember why I have always enjoyed how they sound. I plan to wrap them in a walnut or cherry veneer this winter. I may swap out the tweeters and crossover, but I still have not made up my mind. The last time I looked into doing the driver/tweeter swap, the cost was nearly that of a new set of speakers.
What we clearly need is a version of the speakers where the top portion rotates horizontally to bring different tweeters into play, like the rotating license plates on the old James Bond movies (and Transporter IIRC). A few hours with a remote control for the tweeter rotation and a variety of source material should settle the discussion in short order.
