My only experience with Grado was a pair of 325's (don't know which flavor) . They were very punchy , unnaturally so ....OK for a quick hit of classic rock , but my pref is for more natural , less colored. Didn't appear to be comfortable for long periods.
The more that I use the STAX, the better they seem. But I don't want to forget about my Senn 580's as I've seemed to do with the Shure E3's that I was so happy to buy....IEMs can sometimes beat even the big, expensive cans.