Okay, the UE 4000s have arrived. I haven't listened for very long, but I'd like to give my initial impressions. Disclaimer: I have probably been spoiled in the past with SRH840s, and also probably forgotten just how bad $5 Deal Extreme IEMs are.
I really like the comfort, and they feel well-built without being ridiculously heavy. Israel is a pretty hot country, but I've been able to walk around outside for 20 minutes without sweaty-ear syndrome.
Sound-wise, I've been a little bit underwhelmed. So far we've had Signals by Rush, and the first Velvet Revolver album. At first I was really disappointed, bad artefacts etc... Then I cleared the cache on Google Play Music (Android) and set streaming quality to High (Normal is the default). They sound... fine. I mean, not offensive or anything, but not really making me go wow. A little muffled / veiled / fake perhaps. I'm not sure if this is the bass punching too hard, or just a lack of clarity at the top end, I find it hard to describe sound with words. I checked my phone a few times to make sure there were no EQ or sound processing involved.
To be fair, for $20 plus shipping (yes I went purple), they are great. I need to keep my perspective and remember I was on a budget this time. But I'm keen for the UE 6000s to arrive, to see how they compare. Plus of course, I might appreciate the 4000 sound signature more over time. I will also say that being comfortable on the veiled side, means that I should have no problem to listen for a long time without fatigue.
I've used the mic as well on a phone call - nice bonus. Sadly the volume buttons don't work with my Moto G, but that doesn't bother me.
So thanks for the recommendations, and I'll report back when the 6000s come.
PS I don't recommend the purple, it's brighter than it looks in the pictures.