Never used IEM's myself, not sure if I would like it, as I feel a need to hear, especially the drums, acustically. This is also a studio issue for me with headphones, I use it slightly sideways on one ear, the other ear is free to hear the actual drums. I guess I could just use one instead of both ears, but with a cable connecting it etc... I just prefer the simplicity of a monitor, and haven't really encountered a situation that needed anything else. The biggest downside though, volume level is high when playing heavy metal, it does do damage to my ears over time. I have a hearing loss on my left ear especially, which I think comes down to the monitor being usually on that side of the kit. Maybe I should just get accustomed to IEM, try it out at least just for that reason alone. But just seems like more of a hassle, especially when using a bigger kit.