The dip around 4kHz could lead to harsh sounding recordings. The reason is that in order to let an instrument sound realistic you use your ears and knowledge of how that instrument should sound. A possible way to use it is to either EQ it in (filling in a dip is generally not a good idea) or to realize that when you are EQ'ing in something to give it more 'bite' that you really shouldn't when it is in the targetted frequency range.
When you want cheap and 'neutral' and closed the K371 or K361 may be a logical choice.
In open headphones there are some other options but most of them have roll-off in the lows. This isn't problematic when mixing because you end up with a meatier/bassier end product.
Tonally the K371 is hard to beat at that price point. The fact that some people prefer a different tonality and consider that more tonally correct is more of a personal preference or listening level thing than anything else.
The K371 and K361 may well not be the best choice for listening enjoyment (the microphony completely destroyed it for me).
So while very good in certain things, not so good in others.
It's a trade-off.
I see, that makes sense. I'm not against open back, closed would just be more versatile. What open back options would you recommend?