I lived on Tavistock Road (W11) for 3 years (early 90's). As a local, I knew which areas to avoid, one of which was All Saint's Road, which intersected my road. Overall, the atmosphere was great... but as the sun went down you went home. The police presence would ramp up and it was clear they were expecting trouble.
It wasn't my kind of music, but when I was young, I genuinely enjoyed the party atmosphere. I wouldn't go now, primarily because I am an old man with a weak bladder (or is it a weak man with an old bladder?).
Ultimately, if it were as dangerous as some people seem to be trying to suggest, only scumbag thugs would attend.