I took the plunge and upgraded to these from a similar, but much cheaper Shure model (SE102). I have been very disappointed.
First the good: when they're in, and stay in, the sound is great - powerful and neutral. They look solid, with a thick and long (too long?) cable. I bought the CL clear model, which is identical to the black in other respects.
Now the bad: getting them to fit is a pain, and even once properly adjusted (you have to bend the last stiffer couple of inches of cable round your ears and choose the right tips) they easily fall out or simply move enough to ruin the sound isolation. I find myself constantly adjusting them when walking, let alone running. All this I could live with, but I am now attempting to return them after 3 months as the right side keeps cutting out. Shure have designed these with a cable that plugs into the earpieces, a very good idea in theory but not in practice. The slightest head movements cause the sound to completely cut out on the right side, which is completely unacceptable. Reviews on the web indicate this is not an uncommon problem with this model (e.g. on amazon.com).
As a fan of Shure's SM microphones I really wanted to like these...but no.
Update: I bought these via Amazon from DAQ, who Shure now tell me are unauthorised to sell their products and are refusing to honour the warranty.
Latest: Amazon have offered to take the earphones back for a refund.