Oh no, I'm sure they all have very different soundstages.
What I'm saying is that the idea of custom IEMs / these micro dynamic drivers is that there is a benefit to eliminating as much interaction between the sound waves and the ear canal, either by replacing the material between the ear drum and the driver with some other material besides flesh (the canal tip of custom IEM's) or by bringing the driver closer to the eardrum (JVC's approach). I'd imagine that bringing the driver closer to the ear allows for a smaller volume of air sealed inside the ear canal, allowing for previously unattainable damping factors - perhaps the reason why sub-bass is a signature of JVC's micro drivers and my own experience with the CC51.
Meanwhile the large angled driver full size headphones take the opposite approach - embracing the flesh and relying on the surface of the ear to shape the sound in a way that we are familiar with.
I suspect both approaches work better for different types of recording (studio vs live vs binaural). I've found for instance that the SA5000 works much more naturally for binaural recordings than anything else I've tried.
Edit: Ah, just saw your edit. Well, I dunno. I think every headphone I've tried with angled drivers have a more natural, more 'in-front-of-your-face' soundstage than headphone with drivers parallel to the head. The SA5000 vs the AD2000, or the Z1000 vs the Pro700 as far as my inventory goes.
Edited by a_recording - 6/10/12 at 8:43pm