I was looking through the streetart category and thought, wait, I know this place - no that can't be. Well, I actually do know it, but when I were there last this awesome graffiti wasn't, so thanks for sharing!
I was teasing but actually you gave me food for thoughts. I'm not into street art that much, I think it depends. Obviously it's not ok to just spray over someone's art (especially when it's good quality in any way), secondly, I've heard rumors about one street-artist being stabbed or attacked by members of other clan/gang/group so obviously don't make enemies too strong to handle (unless you are willing to), and lastly, I'm sure that there's plenty of space for everyone even in popular places (still so little people spray ground it's a shame! even if life span of ground-based works is very short I would love to see and step on grand murals on pavements or literally streets).