While i've never heard a Plasma tweeter, i've been told by others that i trust that there are NO other options once you've experienced them first-hand. Their speed is unmatched by any type of driver based on a physical material. In specific, the Hill Plasma drivers were bone flat out to 40 KHz and remained linear out to appr 100 KHz if i remember correctly.
I know that our friend overseas ( the magical and mystical Detlof ) uses Plasma tweeters with E-stats for mids and large planars for bottom end. He's a good guy and would probably be glad to fill you in on specifics such as benefits, drawbacks, safety precautions, etc...
I can dig up a site where a guy had several hybrid dynamic / plasma speakers for sale. Some were still new in the box if i remember correctly. Drop me an email if you're interested and i'll try and hook the two of you up... Sean
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