wow I missed the big argument! LOL.
I don't want to restart the whole thing but thought I would chime in.
I have owned several of the headphones and IEM's bandied about in the thread and the bottom line is which is "better" will always come down to the individual listener. Someone says the Etymotic sound better than the Quad and for that listener that statement will be true if they really like a very detailed IEM that is ruler flat and slightly cold and analytical. For another person that Etymotic will sound sterile and to clinical where as the Quad will sound warm and inviting. The HD600 is similarly very neutral and will have a similar affect for each type of listener.
As for the idea that multi driver configurations are technically better that is not necessarily true. I have owned a few single driver IEM's that have competed with multi driver IEM's in all areas including sound stage. The reality is if a company can afford to develop a good dynamic driver they can easily compete against multi BA and hybrid designs. So why do companies make these multi BA and hybrid models? Simple, they allow companies with limited resources and development budgets to create IEM's that can compete against a costly researched and developed dynamic driver IEM. Anyone wonder why Sennheiser has been using only tweaked versions of the original IE8 driver in the IE80 and now IE80S model IEM's? Because it is damned expensive to actually develop a truly unique driver like that in house. Beyerdynamic has similar cost constraints on their proprietary Tesla technology. Multi BA technology on the other hand allows for a simpler approach to address limitations and is also more repeatable but at the cost of cohesiveness that is achieved by single driver solutions whether they be single BA (Etymotic and other brands) or single dynamic solutions like the IE8/80/80S model by Sennheiser.
Now lets talk marketing vs advertising for a minute. True marketing is where someone researches a market and develops a product to meet that market. So if a company see's that people really like multi BA and hybrid technologies they will then develop products that meet those market expectations (thus the glut of Chinese made Multi BA / hybrid designs that have flooded the market over the past few years. Advertising on the other hand is where a company spends money trying to convince people of their products benefits and more often their "Brand Name". This is where the Beats and Bose come into the world. They rely on advertising dollars and brand association to sell their product versus actual technical prowess. Unfortunately modern history has shown that advertising works, thus the overwhelming glut of mediocre sounding celebrity endorsed "stuff". Where life gets interesting is when companies mix marketing with advertising and we get products that are look like they should be technically advanced but in reality they don't sound technically advanced at all because the manufacturer just cobbled together a bunch of technological concepts rather than truly developing an actual well crafted product. These companies rely on people seeing buzzwords and technologies and assuming this means the product will sound better simply because of that. They in essence use the market as an advertising tool. They are like companies that make knock off products but instead of blatantly faking products they simply just fake the technological concepts.
Sites like Head-fi exist to help people combat false marketing and advertising campaigns. The challenge is that sites like Head-fi also end up with opinionated hotheads, elitists, well meaning people with limited but very enthusiastic opinions, and to be blunt a few shills. To combat this myriad of challenges members of Head-fi should research not only the products they are interested in but the people who are posting the comments. Find out if a poster is simply and enthusiast of one product or whether they have owned other brands to offer true comparative opinions, is the poster someone who prefers a specific sound profile over all others, does the poster feel the need to convince others of the superiority of their chosen products over all others, does the poster rely on third party references over actual experience etc. Finally members should recognize when a thread as has fallen into an argument and take all of the related posts with a grain of salt because emotion and the natural instinct to compete have over shadowed the original intent of the thread.
So where do I stand on the Quad?
I think it is a technically solid IEM that offers a very nice bridge between bass oriented mass products like Bose and Beats and audiophile level equipment. It will allow someone who finds that commercially mass appeal products to be a bit to "safe" and boring an opportunity to experience something a bit "more". It will introduce those people to the fact that music can actually have a 3 dimensional sound field, that music can have more emotion and edge than they realized, that there is a world of minutia and detail in their music they never knew existed... From there the listener might simply STOP because this new experience is satisfying and enough for them, or they may use the Quad as a gateway product that opens them up to newer products that intrigue them. They might love detail and minutia and go down the Etymotic IEM pathway, or end up buying an HD600 and 2 years later find themselves owning an HD800 variant. They might love a euphonic sound with a massive 3D sound stage and buy a Sony XBA-Z5 or MDR-Z7 or higher, they might venture down the planar path, in the end the sky is the limit.