This stuff is the absolute business. Have a read of the Opie oils site on the issue... it exceeds 5.1 standards
Yes it is, but it absorbs water pretty quickly so needs changing often, I have read as little as 4-6 months, also needs changing if you boil it. Good for track-days though.
5.1 is a good compromise, and you shouldn't manage to boil it on the road in anything other than exceptional circumstances.
What do you think of the ds2500's? just put these and some braided lines on my civic, they just bite harder and harder the hotter they get. Very impressed.