Hello  
 
I don't write here often  
 
I wanna write something about the HE60.  I tried them out, because I'm a Grado head, and while they have a more forward presentation, they lack the deep bass of the OmegaII, which I like a lot.  However, they don't lack bass and I do find them to have more or equal bass than some other popular headphones like the K1000. 
 
They do give a unique forward presentation, that does not ressemble the Stax presentation, and they do excel at certain song.  They surely give a nice contrast to the Stax OII to certain people and to me, but frankly, I do prefer everything on the bassy side and I've always been like this.  I find the Stax OII have more bass than most Grado headphones. 
 
As to whether the HE60 are better than other lower end Stax can, I don't think you can compare them so much.  I do think the Sennheiser sound is a different approach than the Stax sound.  I did have a pair of Stax Lambda Signature, and as I remember, they were very nice (and did have an awesome bass), but were totally different than the HE60. 
 
So, if you like the OII sound, but want a totally different but enjoyable taste, the HE60 is a good option.  You like the "darker sound", more bassy sound, even less Gradoed sound (  ), they are not for you.  Are they worth 1000$US or 2000$US in price? I don't know, I paid that price to try them out and was satisfied.  Price is very subjective in the world of audio.