I have found the perfect replacement, well, sort of. I have a pair of PSB 4T speakers I bought new. After they were out of warranty, one of the tweeters stopped working. I purchased an OEM replacement from PSB for about $50+. Then several months later the tweeter in the other speaker stopped working. Another $50+ for a tweeter from PSB. Then just recently a 3rd tweeter quit working. I do not listen to music at loud levels. I firmly believe that these tweeters have a manufacturing defect. I have seen posts of others with blown PSB Image tweeters. I have never blown a driver in 40 years of speaker use. Well, let get back on track.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-1028 This Vifa tweeter from parts Express is a perfect drop-in fit, down to the screw holes. A pretty good match for the crossover point. Nice sound compared to the original tweeters. The only problem is they are very efficient. SPL: 96 dB 2.83V/1m. The PSB 4T is listed as SPL 90 db 2.83V/1M. Don't get me wrong. They sound good, just more "forward" sounding. But at $11.95 vs. $50, you can't go wrong. At least to my ears.