I’ve heard the Momentum 2.0 and the original K550 and K553; you’re right the Momentum 2.0 is incredibly dark. I wasn’t a fan of them. I actually prefer the original Momentum as I feel the bass is slightly cleaner and the midrange isn’t as colored, but I still wouldn’t pay more than the $40 that renewlogic on ebay charges for a used one.
Going to the K550 is a pretty big switch because you actually get treble and upper midrange. There is some grain from what I recall but honestly, it’s probably my most recommended closed headphone in this price range if you can get them to fit right. It’s not perfect by any means but I feel it does the least wrong.
Though if you’re treble sensitive, I’d suggest maybe trying the Beyerdynamic DT770 and swapping the very treble-forward pads for the Shure SRH1540 pads. I normally don’t support pad swaps, but my friend did a DT770 mod that used these pads and some additional internal damping and I thought they were pretty good.