First off, these things are drop dead sexy! The wood grain is very nice to look at, and has no scuffs or marks on it what so ever. The acrylic housing is also really nice, It is a deep purple, and it has some metal flakes in it to make it slightly reflective. It is also slightly transparent, so you can see the inner workings of the IEM. As far as fit goes, they are quite comfy, not quite as comfy as my old SE535’s were, but very close. A big part of the fit is getting the right tips for your ears. (I am using the medium blues) These are a very neutral, accurate IEM. Nothing seems to be over emphasized or recessed. The bass had a nice punch, and is textured very well. The midrange is not as lush as the 535’s were, but I find that it is more accurate. For example, in Brian Kahanek’s One True Thing (same name as the album) the guitar has a certain emotion to it, and these convey it very nicely, but you can also feel each separate pick of the strings as well as the amp slightly hissing when he plays faster. The shures could never pick this up, I felt that there was a slight veil that obscured the details of the midrange slightly, that the 4.ai does not have. The treble is IMHO one of the strong points of this IEM, not rolled off like the 535 were, and it has some sparkle up there, but never any sibilance. Soundstaging is very nice for IEM's, quite open, and feels like they are full sized cans rather than IEM's. Positioning and imaging are also top notch as well.
Are these IEM’s worth the $400 price tag? Yes, they are, and I would go as far to argue that they can easily go toe to toe with more expensive offerings from other companies, and win.