Let me add to it.
The Shure IEM's will let you hear your mix no matter how loud it is, but they don't do well if you are having to put them on/take them off continuously. The foam tips need time to fit correctly each time you insert them, so it's not nearly as quick or thoughtless as a closed back can.
OTOH, they are so good at blocking noise you won't be running the signal to your ear very loud.