Purely conjecture on my part.
I've noticed that since HT has become the driving force, speakers have gone from the classic big woofer, big box system to a tall, skinny configuration with multiple smaller woofers. this is all well and good but, to my ears
(and some others I know), they lack the visceral "impact" that old fart rockers like us miss.
They depend a lot on subwoofers to make up the difference but, IMNSHO, subs come in at too low a frequency to fill that hole in the soul.
Now, don't get me wrong, I'm not a bass head but different strokes for different folks and musical styles. My main system consists of speakers that are more musically "accurate" and for almost anything but rock they are superb, but for that good old rock and roll, nothing beats a "classic" speaker system with some mid-bass kick.
Those speakers I mentioned are not what I would consider "accurate" in the traditional sense of the word, but sometimes ya simply want a big, greasy cheeseburger instead of beef Wellington and for that, they do satisfy.
The classic JBL's are the standard-bearer of this type sound and the old CV's aren't too far behind. The DCM's are only about 10 or so years old and should still be relatively obtainable.
As for quality, I'd say they are all good. As for the price disparity between the JBL L-100 and the rest, well, consider it the '57 chevy of rock speakers. Not necessarially "better", but it's an icon, which adds to it's market value.
And, ya know what? you don't have to make a life-long commitment with speakers either. You CAN have your cake and eat it, too. That's where A/B speaker selectors on receivers come into play. I've got an eye out for a nice, reasonably priced pair of AR 5's for my system for the "non-rock" music I also love.
Oh, did I mention we're going to see NRPS this Friday at the Stone Pony in Asbury Park?