^ A clear step up? No, definitely not, if by that you mean a night and day difference. But, like so many things in life, a small difference to some may be a more significant difference to others. Well, I happened to pay £1000 ($1,550 USD at today's exchange rate. I know the K3003s currently go for $1,300 in the USA). I paid $500 for my EX1000s. Here, the law of diminishing returns is a very, VERY real thing, ie to these ears you do get an improvement in SQ, but I'm convinced most people (ordinary people, that is, and even some so-called audiophiles) would not be able to easily find the K3003s that much better sounding, let alone twice or three times better sounding.
You are well aware of my stance on custom IEMs which, on the whole, I consider downright overrated, ie I strongly believe there's too much hype and exaggeration just as there is, in my view, too much hype and exaggeration when it comes to bitrate differences and the seeming mandatory use of lossless files, or at the very least the need, according to some, to listen to 320 kbps files when it comes to using higher-end phones. Same [or (much) worse] goes for aftermarket cables and, to a lesser extent, portable amps.
Then, there's the usual variables such as sound preferences, fit issues, and so on. Already someone's said they prefer the 'treble' filter on the K3003s to the other two - to me the 'reference' filter is by far the better sounding of the three. Someone else said they found the treble on the AKGs rather 'troublesome' - so, here we have the usual differences we find in almost every IEM we talk about.
Yes, the K3003 is a very, very good sounding IEM, and it'd better be at that price! But, inevitably, expectations by some/MANY people (because of the price) will inevitably be very, very, VERY unrealistic. I'm sure in a blind test most people would very likely enjoy the K3003s, but there would be those who'd say they find a different, and (much) cheaper IEM better or similarly sounding. Some would just say: "Yeah, it sounds nice/great, but I wouldn't pay more that $100 - $150 for it.
There are people who will buy any and all high-end IEMs because they can afford them or for other reasons. There are also people who are very good at regurgitating audio jargon causing many to think that a particular IEM is truly something else. There are people who are prepared to pay a [very (high)] premium for a small increment in SQ…etc., etc., etc.
The EX1000 remains, in my view, an amazingly good sounding phone.
All that said, and for what it's worth, the K3003's midrange, to these ears, is simply unparalleled by any other phone I've heard.
I haven't seen you much around here lately, music, and posts like this are sorely missed. Honestly, they're essential to bring things a bit more down to earth. I agree with pretty much all of what you say.