As a person who spent many a tormented hour comparing the PS1000 and PS1000e (really, I lost sleep and nearly got fired from my job because of it), I can tell you that they are obviously from the same Grado pedigree ... but at the same time, rather different in what they focus on.
The original PS1000 has a quite noticeably colored, affected quality, almost like a "built in" EQ setting with the bands set to a "U shape" ... a definite emphasis on the highs and also a spike in bass; the midrange on both are about the same if you ask me, typical rich and forward Grado midrange (unlike the more recessed GS1000 midrange).
The newer PS1000e takes that above mentioned "U shaped" eq setting and flattens it out. The PS1000e is far more neutral and "flat" sounding than the more colored, more affected PS1000. Certain folks will prefer one over the other. Myself? I ended up preferring the more lively, energetic PS1000 over the PS1000e.
I've read many times here and other places that the PS1000e, supposedly has better sub bass but I didn't hear it with my particular pair of PS1000e's .. in fact, I found the bass to be almost "sucked out" with the "e" version; I've very near ordered another pair of the PS1000e's, on more than one occasion, just to see if perhaps I had a weird pair cause the bass was almost anemic compared to the PS1000's ...
Fans of neutrality will definitely prefer the PS1000e as they really are rather clinically "flat" to my ear (or were) ...
I may still order a new pair of PS1000e's ... just to put to rest some questions I still have about comparing the two ... and I'll post some thoughts here if I should ...