It's hard to describe, but it's something you can't see on a meter, because you have a complex amount of tones going through it (music). One way I test things like this is to run them in parallel with one out of polarity, sum them together and null them. You can then hear what's different, then go back and find those things in each. This method works well for comparing mic pres, matching EQ settings and matching compressors. It's all about training your hearing. To me, open makes me feel relaxed and happy, pinched makes me examine it instead of enjoying it.Define "open" and "pinched". Someone has to invent an openness meter and a pinch meter.
Several have undertaken the issue, and came out with current feedback opamps.
Some are quite remarkable, e.g. LT1795 or ADEL2020. They are not cheap though. They are not plagued with the G.BW limitation. For some reason audio designers have neglected them, so the only available are not really suitable for audio; they often lack voltage headroom (due to low rails) and are optimized for high output current, which is not always necessary.