Adrian
I think you're right. I would be wastefull to use a 4590 in conjunction with a midrange driver. On the other hand it would end up as a really cool system. But maybe one of the 1" compression drivers are a more practical choice.I have heard that the 4590 and the 4592 neodymium should be really awesome. However I haven't personally heard any of them.
What i have on shelf is a couple of jbl 2245 and a 8" focal axiom midrange driver which i suspect could be used instead of the jbl 2123 in an audiophile system.
cheers
andreas