Everyone has an opinion based on their own individual preferences. It depends on what you want and what you're willing to put up AND pay. I'm not willing to put up with open-back headphones, so my opinion really doesn't matter cuz I'd never buy one. lol Most say they do sound better, but not all. Just look at
this video review comparison. You may disagree with him but if you were to actually try both out like he did, you might surprise yourself. lol That's why I say, use reviews as guides, but know that you're never gonna be 100% sure unless you review the items yourself.
I just remembered............when I
did compare my old AKG K553 (which sound EXACTLY the same as the K550) vs. the Sennheiser HD 598 SE, I found the K553's soundstage seemed to be just as wide as the 598 SE. So I guess I would disagree with the reviewer you posted. lol