HD 550 vs HD 650

So, I am torn between these two sennheiser headphones and I can't decide.
I made my little comparison table but I can't come up with a decision.
I think the HD 550 is more for me for how I would use it (at the desk, plugged to monitor or I will get the hiby w4 because I like the idea of a device so flexible) but the 650 never goes fully away from the picture.
Who had both, how would you describe them?

For context:
I listen mostly to rock, metal and blues but I also throw in the mix European folk, pop, and electronic.
I really like having nice vocals and I get bothered when recordings make the f and s sound's sibilant so I am looking for a nice and forgiving treble (this is what I think I want).
I don't have experience with open back only IEMs (currently using the Meze albas) and wireless headphones.