Yeh we have an oil filled radiator in our bedroom too, they are pretty good.  I love the safety sleep though, cos I sleep better at nights knowing that they are not getting themselves anywhere or into danger.  I have used them from birth so they get used to them.  Then just as they are gettig smart and can open the velcro, I have safety pinned them!  That doesn't stop them kicking the covers off though, so I wrap them round the middle with a fleecy blanket first before I belt them in, and they cannot kick that off!  The hands getting free is a different matter!  They always wake up and they are snug and warm but their hands are like little ice cubes!  So we decided to get an oil filled heater this time too.  We are inching the cot towards the bedroom door at the moment---lol---like you do when your getting ready to put your baby in another room.  We disturb him and he us most of the time and I feel he would sleep if he were out of our room now.  After him there are no more, so it's all boxed and up in the attic until the grandchildren come along no doubt. 

JH