Early revision had 4 screws and was not only differently tuned but also technically better. Better imaging, separation, more airy, sharper transients (not as sharp or square like the HD800) but also brighter up top.
It is the best version but needs more modding than 6 screw, especially Blu Tack. HE-6SE is a 6 screw HE-6 in a new casing and has better dampening applied already.
I wouldn't make a big deal out of it, it's not like the 6 screw HE-6 is a bad choice next to the 4 screw. In fact, it's more that the 4 screw version has become rare and people love to apply the unicorn status to it. I listened to the HE-6SE recently and it's a great headphone which if my 4 screw ever died
I'd be very glad to have. Of course the qualities my 4 screw brings isn't something I'd easily brush away.