Interesting, I've demoed the IM70 and E40, and very briefly the LS70 and LS200 (no time for LS50,300).
To me the E40 really smokes the IM70 in clarity and naturalness of sound across genres. The interesting thing is the LS70 feels too me a very big step up in sound from IM70, still bassy but less muddy and more energetic overall.
It may not be a bad thing, but i found the LS200 very flat and uninteresting. Precisely that may have been coherent tuning not sending any red flags to my ears, but i will need to go back and listen again. Definitely can see where others' LS200 opinions are coming from though. I'm just thinking I'm getting twice the sound of the E40 as where i am the E40 goes for half the price of the LS200