First let me start off with the weaknesses as perceived by an SE530 owner.

The Shure has the advantage in mids, I wouldn't call the Westone mids recessed, I would just say that the se530's are exaggerated (in a good way). This makes male vocals sound a bit more foward and pleasant in the Shures. The Shures also have a bigger and wider soundstage about them. However, I think this comes at the cost of accuracy and detail.

Now onto the good. Overrall the Westone 3 is the superior IEM. All the INSTRUMENTS sound better and more realistic in the W3. The bass is also better; more defined, pops harder, and quakes less compared to the SE530. There is higher accuracy in every other part of the sound spectrum as well; the highs are much better, I can hear the pick hitting the string whereas on the Shure I could only hear the string itself.

This extra accuracy does have some downsides though. I have experienced a bit of sibiliance for the first time in certain songs. Also, I find these much more fatiguing than the Shures. I chalk it up to the better highs.

The comfort is superior to the Shure's, which I had zero complaints with. It's not that the earpiece itself is nicer, but the lack of the Shure's thicker/heavier cable hanging from your ears makes them disappear on you. Speaking of the cable, this thing is awesome. It is soft, very bendable, thin, light, and seemingly durable. The thin and bendable qualities also make it so you don't have to worry about it ever cracking where it folds over your ear. While my Shure's did not have this problem, I could definitely see how it might occur given enough time.

Overrall, the only small downgrade from what I had is the mids, but it's a small price to pay for the better everything else.

Credit to: Jensen, head-fi.org (Other Westone 3 reviews)

Westone 3 New 3-way Driver