Ok...testing on the 480s that came with the EF-61s I bought and need to turn around and sell, they're actually not that bad, though not quite what I'd call satisfactory.
They are, however, several cuts above the TW-24. I suppose by the general standards around here, it's a pretty good tweeter...but not to me. I'm spoiled, see. My first entry-level bookshelves were Wharfedales, and the tweets on those things have me spoiled rotten. The only tweeters that satisfy me now are Ascend Acoustics, and that's the standard I'll hold anything else to...
So, once I get my digital camera, these ES tweeters are going on sale. The "quiet" part was the lack of a crossover, but these just aren't 'solid' enough, IMO.
They DO make an excellent match with the EFs I have, however.