Woah, pikaa, 1200 fps is pretty darn crazy :O
When used wrongly, anything could be dangerous. Like if you intentionally try to hurt someone, you sure can. With good friends though, it should be no problem. A lot of my friends have airsoft battles all the time (well not so much now that school is so overwhelming). The worst they ever get are some small welts and bruises, nothing that lasts over a week. Actually one of them was shot point blank due to a dare. THAT one stayed for a while :P
use common sense.
Also, compared to painball, airsoft is pretty darn docile.