We have co-slept since DS was about 8 weeks old and he is now 16 months old and still sleeps with us at least half of the night. I make a point that he always starts the night in his bed though. When he was little I had one of the anti-roll thingos to prevent either of us from rolling on to him and that worked well. Now that he is bigger we don't need that and he sleeps in between us just fine. He has a feed, then scoots himself up in between our pillows and falls asleep. It works perfectly as he can sleep uncovered, but we can stay covered and warm. I love co-sleeping as it lets me get more sleep and I don't have to get up and freeze when he needs a feed.
Every once in awhile he gets too unsettled and then DH will take him into the spare room and they will sleep in there which means for some reason DS settles and sleeps better and I get a good block of sleep. Both beds are double beds. I hope that helps...