What about that description puts you off?
My personal opinion is that "hi-fi" has come to mean anything but, usually with lots of high end sizzle and a depressed midrange. Actual hi-fi means flat response, no frequencies accentuated or suppressed. That's what the JBLs are like. I have a 200S cabinet with the original JBLs that has been tested as virtually flat from 50Hz to 2000Hz, with a well-behaved 12dB/octave roll off above 2K. That's the kind of response you should expect if you dig up some JBL D140 drivers. For a lot of people, that results in rather more low end than they like. Not big, boomy bass, just really low. A lot of amplifiers and speakers roll off the low end for various reasons, so most people have never heard what 50Hz sounds like. As a result, a lot of people think that a big boost around 100Hz is what deep bass sounds like.
IMO, nothing would sound better in those cabinets than D140s. However, those drivers were designed back when amplifier power was expensive, and there was a premium on efficiency rather than high power handling. They're not going to like a kilowatt on a low B. The K 140 should sound exactly the same, but will handle twice the power.
I find it interesting that the Eminence 1518 strikes you as lacking midrange. It actually has a fairly large peak in its response in the midrange. See the response curve:
If the 1518 lacks midrange, then you really wouldn't like the JBLs.
