LCD2 is probably better than the HD800 or PS1000 if you're an old-school hip-hop fan like your profile indicates. I was in your shoes two months ago and was about to shell out for a PS1000 until I went and demoed some equipment, and ended up with an O2 instead. If I didn't go for the O2, I would have ended up with the LCD2 or HD800. If you're looking at $200-400 headphones, I think Grados are a top-5 choice, but the competitiveness drops off sharply once you get into the flagship tier.
I wouldn't get the PS1000 unless you absolutely love the Grado sound, and I also second what people here say about demoing first. Last but not least, as TMoney stated, resale value is going to be poor for the PS1000 if you decide you want to recoup your investment.
Anyway, I'm speaking as a big fan of J Dilla, Pete Rock, Premier, and RZA production, and my hip-hop playlist consists of everything from Big L to Little Brother. For hip-hop, I'd go for a warm, analog sound, which is why I'd immediately default to the LCD2.
What amp are you using or plan to use? Also, solid state or tube? That would also probably inform the decision quite a bit.
Not sure what's with the hip-hop hate. The point of expensive audio gear is to have fun with whatever you love listening to. Hip-hop sounds awesome on my 'stats