I’ve had both the Etymotic E6i’s and the V-Moda Vibe Duo’s. I think I liked the Vibe Duos a little more. They would be perfect if you create a custom EQ setting on your iPhone. Why you can’t, I have no idea.
The V-Moda’s are also $50 cheaper than the Etymotic’s. And with the V-Moda’s you don’t have to deal with routinely replacing the speaker core like on the Etymotic’s
My Vibe Duo’s had a malfunction after about 5 months, where one of the ears wasn’t working properly. I contacted them about and they offered a replacement, no questions asked, and assured me that they’re making a new batch that had any potential issues worked out. On top of that, those won’t be in stock for a few more weeks, so until they come in, they sent me a pair of the V-Moda Vibe headphones absolutely free ($100 value) until the Duo’s came in, which they will be replacing as well. Excellent customer service worth mentioning.
P.S. my Etymotic E6i’s died eventually as well, right after the 1 year warranty expired
P.P.S. The other nice thing about the V-Moda Vibe Duo’s is the fact that the 1/8” headphone jacks fit perfectly within the iPhone recessed output jack. No need to a 3rd party adapter.