No, when I purchased my 535's from Headroom, they didn't have any Westone in stock (that I recall, it was several months ago). I tried out similarly priced Sennheiser in-ear headphones (ie80 and ie800) as well as another higher priced JH Audio IEM model (JH13, iirc), but the 535's sounded the best to my ears.
I do see that the Westone's offer 4 drivers to the 535's two drivers, but unfortunately Headroom doesn't have the frequency response graphs for them yet. Otherwise, they seem very similar for features & specs (they both appear to use the same ear tips, which is good for finding the one that fits the best).
Of course, I'm lucky enough to live in Headroom's home town, so that helps these kinds of purchases immensely.