Heard both, have W4 - honestly if you HAVE to get something different the W4 is the way to go if not willing to take the gamble on customs (because the ES5 is TOTALLY in your reach at 1000).
That being said, I love the W4 but it's not a LOT better than the Shure 535. It's just different and one could only call one better than the other by preference. I'd probably listen to a few different IEMs and see the kind of sound you like: for example with that kind of money, you could probably get both the high end phonak and the W4 and see which you like better. OR you can take the k3003 for a while, although it's slightly outside of your budget.
There are a lot of things to consider, but with a budget like that, you are bound to find the sound you want; if not with one IEM, then with two - I know I went through the same phase before ending up with both the W4 and UM3X to cover all of the genres I listen to.