When I was at AES, a Shure representative suggested the SRH440 for mixing— which is at the lower-priced end of the line—because he felt it was more accurate. When someone in marketing recommends a lower-priced product, that gets my attention!
But Shure sent both the SRH440 and SRH840 so I could decide for myself. The rep was right on: I much prefer the 440 for its more balanced response, particularly in the low end and low mids, that would make it better- suited to mixing. The 840 seems to emphasize the high end somewhat, which is okay when listening to commercially- recorded music but not as helpful when mixing.
So let’s look at the 440. Its level of comfort is average; you would have no trouble using it for hours at a stretch. The ear pads cover your ears well, and help reject noise. Like other headphones, it comes with a detachable coil cord and 1/8" to 1/4" adapter; but the end that goes into the headphone can lock, making it difficult to pull out accidentally.
The overall sound quality is slightly less transparent than more expensive contenders, but that’s the tradeoff for the lower price. The crucial point here is the response (which tells you the truth), and the low cost.
In terms of value, you simply can’t beat the SRH440. It may lack the finesse of higher-priced models, but for mixing, it does the job remarkably well—which is even more surprising, given how kind it is to your wallet.