Do not replace the tweeters. A better tweeter won't necessarily give better performance; loudspeakers are systems. You might get a few things better with the new tweeter, but you'll probably sacrifice a whole lot of other things because that tweeter isn't being used in an optimized condition (crossover freq. may be off, etc.)
Replacing my tweeters a good idea?
I have a pair of infinity Delta 70 loudspeakers. They have 2x8" 1 6" 1 4" and a metal tweeter. They image superbly, and set a good soundstage. People think infinity are bad, but they are great in my ears, apart from the metal dome tweeter. It gets a bit harsh on some recordings. Is it possible that i could replace the tweeters with something else, say dynaudio tweeters? would it be worht the trouble? I am not getting new speakers.. so dont bother trying to say that. :P thanks