ive played with pretty much all of them that have 6.5" except the MLK3's on the display and in cars
HSK, on the display boards, are a tad bit heavy in the mid range freqs, more efficient
MLK are alot smoother, "brighter" tweeter, not harsh, just more in your face, midbass is close on the displays, edge going to MLKs
but your looking at a 2x+ increase in price, on their own, both sound good on their own, just when u put them together, u can tell the differences
our demo room before it was finished, have the glass in there now where the boxes are, u cant really see it, but mlk2 is the bottom piece