I definitely prefer the SA6s over the earphones I have owned: Westone UM1, UM2, Super.fi 3 Studio, 5 Pro. I have only tried the Etymotic ER-4S and UE TF10, the TF10s are too imbalanced (to my ears) and the ER-4S are different with even more treble detail, but a bit less bass.
It depends greatly on what type of music you like. I like rock, jazz, and classical. While the ER-4S have the edge when it comes to classical the bass of the SA6s makes them better suited for rock, in my opinion.
I hope you find a pair of IEMs that suit your needs.