Ok, the only CIEM I have heard of competing with high tier headphones is the SE-5 Way, but I don't want a silicone IEM as they are less customisable and seem less durable. In A review they compared it to the LCD-3 and said that it bested it in most areas apart from soundstage. Will be on the look out for any CIEMs that testify to the same claim.
Just so you know, you won't be able to customize much with the FitEars either. There's a total of 4 shell and body colors you can choose from (Black, Blue, Red, Clear) and you can choose your canals to be either clear, blue, or red. You won't be able to add any custom art or anything to FitEar CIEMs.
Silicone CIEMs are not less durable. In fact, because of their pliable nature, they're prob the best if you plan on dropping your CIEMs on the floor (of course, this is all hypothetical). However, silicone CIEMs may take some time to get in and out of your ear.
If I were you, I'd ask yourself, "In what setting do I listen to music the most?" From there, you should be able to decide whether to go IEMs or full sized.
Personally, since I know I'll be heading to university next year, I'd prefer something that's easier to carry around. Also, I find that the isolation IEMs provide allow me to concentrate on music more, since it is directly beaming sound into your canals while blocking out external noises at the same time. Yes, it is less "natural" but it also allows me to pinpoint details in my music more easily. Of course, I am envious of those with full sized setups and actually have the time to listen to them. The general air and feel of full sized headphones cannot be replicated. By that same logic, headphones will never be able to replicate the air felt from speakers. It's a matter of physical size that separates these classes. But I believe I've made the best compromise for myself. I listen to a majority of my music either : on the road, in bed, in a noisy environment, on a computer. Hence, I plan on investing all my energy into one setup that will allow me to appreciate my music over the majority of my time. Hence, this summer, I'll be visiting Jaben HK to get my FitEars done.