So I've done some more A-B comparisons between my SE535s and Westone 4s.
My setup:
iPod Classic --> Moon Audio Silver Dragon LOD --> iBasso D4 Mamba --> IEMs
Overall, I do find the Westone 4s more "balanced" with bass/mids/treble. The SE535s have a stronger focus on the mids (and likely the best mids of any IEM I've heard). Bass response between the two is about similar (depth, control and detail), if you only concentrate on the exclusively on the bass, but with the more forward mids on the SE535s, the bass can be a little further back with the Shures in the overall picture.
Again, the mids on the SE535s are forward, lush and very smooth. The Westone 4s put the mids into more equal representation wit the bass and treble. They are not recessed as I found with the Westone 3s though and really quite good and accurately portrayed.
Treble is a tougher call. Both seem very well extended (unlike the drastic roll off of the SE530s), but overall I think I prefer the slightly smoother treble presentation of the Westones.
Sound stage both are on par left to right, but I think I give a slight edge to the SE535s for front to back imaging.
The SE535s are the sturdier IEMs...no doubt. I can use the cable as a bike chain if needed, but that sturdiness does come at a cost: ERGONOMICS. The cable can come off a bit stiff and harder to roll behind your ears and they are heavier (IEMs + cable). The Westone 4s, while not as sturdy, are the more ergonomically friendly IEM: light, with a great cable that just fits very well.
Hard to call a winner here still though, I love the liquid/lush mids of the SE535s and find them quite seductive in that regard, but I think I prefer the "total package" presentation of the Westone 4s by a small margin. You can't go wrong with either one really.
EDIT: I forgot to mention the all important noise isolation --> Winner = SE535s. While the W4s are great in this regard, the Shures are still tops here.