NO!! Don't do it! They play, talk, trash the bedroom together and drive you nuts when they don't go to sleep until midnight!!!!! I regret ever ever doing it!
My two talk but have never trashed the room or stayed awake until midnight. We are having problems now that dd1 is 13 and dd2 is 9. Dd1 has a later bed time and thinks its ok to watch tv in her room, which keeps dd2 awake. Having friends sleep over is an issue as well because of the age gap. Everything was fine up until dd1 started high school though. I need an extra bedroom.