As a side note to this interesting thread, keep in mind that many established custom iem companies, and some newer ones, have their primary market in pro-audio and stage musicians. Head-fi is a tiny, tiny, tiny slice of a large audio market with many facets. There's a custom company which has a small presence on head-fi and they are absolutely flooded with business--pro-musician business, that is. I'm not naming names, but there are even custom companies who don't care a bit about hf because their business is doing very, very, very well and they know very well that trying to over-grow could lead them away from the high-quality service and attention to detail that their rockstar clients expect. We've seen that last outcome happen several times on hf.
On the other end of the spectrum, Skullcandy is actually the largest sellers of earphones in terms of sales, but has little presence here. Think about that.
So, yeah, it's nice to see the new custom companies. Aurisonics, for example, is here to stay (although head-fi and everyone outside of pro-audio is tiny, tiny percentage of their customer base) and it's nice to see high-end universal fit iems, too. Just as people have noted, universal fit can be much more convenient in several ways, although they aren't for everyone. One important point with customs is that even with perfect fit--the fit still isn't perfect! Like a universal tip that fits your ear, a custom that fits right still needs adjustment, occasional prodding/pulling/etc. in the ear. Also, some people have weird and wrong ideas about "perfect isolation" with customs when a deeply inserted foam tip can get even better isolation, if that's what one is looking for.
Customs will always have their place and the end fit can be worth the inconvenience (three refits and a rebuild for me--I worked with companies in the U.S. in the beginning, so it was far easier and I strongly recommend working in-country to start with customs). For stage use, customs are mostly the way for more successful bands. A custom shell universal fit like the Tralucent 1plus2 is seriously clumsy for stage use, for example.
So, a new age on head-fi, sorta.