Buy them. I heard the 7s at a meet 2 years ago and was impressed. They aren't as good as low end Stax, but you shouldn't have to pay much for them. The 7 model was very comfy for a on ear phone, I thought.
By the way they are electrets, not full stats. They will give you that window you are perhaps seeking. You'll hear effortless detail and well defined mids. The model I tried wasn't so great on the bass, but the rest of the spectrum was very engaging. Fun little phones if you can get them cheap. I'd say don't pay more than $75-100 (with energizer). They aren't going to be a replacement for your main cans, but are certainly worth having around. I looked for myself a pair of the model I heard but found nothing at all.
