Bought these to allow me to hear the rest of the band while still protecting my hearing.
At first they appeared great; they protect REALLY well against very loud volume levels, are comfortable, and still allow you to hear what you need, if combined with suitable headphone amplification and a mixer.
There are two major downsides thought:
First, they filter frequencies in a way that give a VERY inaccurate picture of the actual source. This is when not plugged in. So you can forget adjusting a guitar amp or tuning a drum by ear when using them. I once forgot this and spent 6 hours fine-tuning a snare in preparation for a recording. When I finally got the sound I wanted, I switched hearing protection. Suddenly the snare sounded really really bad (same thing without any hearing protection, through a mic and so on).
I've since payed extra attention to how they impact the sound and noticed they are so deceptive I would have stopped using them entirely, just for that reason.
Secondly, if you tense up your head and/or neck the "right" way, the headphone opens a gap, letting in a lot of sound.
I'm mainly a vocalist and drummer and have found it near impossible to do any vocals without this happening frequently.
While drumming they stay in place a little better, but when doing fast fills or going across the kit to reach cymbals, it almost always happens - with noticeable negative effect on my hearing.
I believe the core of the issue lies in the "auto-adjustable" band that is supposed to keep the headphones in place; when you stay relatively still, or rather, keep everything above your shoulders still, it works as intended. But the band let's the headphones slip to low, and at an angle where the lowest part is on direct contact with my jaw. So when I move it, the headphones follow.
Had there been a way to manually adjust the size/length of the band, I could keep them high enough that they protect my ears without my jaw interfering.
The latter problem would likely not impact everyone, but I do believe I have a fairly regular-sized head, so I think these headphones are only suitable for people with very large (or at least tall) heads. I have band mates who cannot wear them at all, since they are to large and simply won't stay on their ears.
Regardless of issue number 2, the first one is, in my opinion, bad enough to not make it worth it. Had the drivers been better, one could have used them to get an accurate picture, but they are pretty bad - which is expected, since these are not meant as proper "studio headphones", but considering the other flaws it unfortunately renders them completely useless for me.
Perhaps worth it as cheap tracking headphones in the studio, but there are better alternatives for that..