i just read an article on the meyersound homepage about their own compression drivers, and since there is a constant reference to the JBL2450 i thought you might want to know about it:

from the intro:
For example, in the case of the JBL 2450 4-inch compression driver, our modifications involved replacing the standard plastic connectors with more reliable gold-plated terminals and replacing the titanium diaphragm with an alternative aluminum alloy version for lower distortion. We also rebuilt and damped the stiff 'diamond' metal suspension to extend its life by reducing fatigue and also sealed the voice coil so we could use ferrofluid cooling to improve power handling. All these modifications were very time-consuming and costly to perform - making an expensive part even more so. We also felt vulnerable since we were a small customer of the only supplier.