I have not used that either, but I have heard from various sources that those are not always that reliable. It can sometimes cause more stress than it's worth. I second the idea of the fan. Also you can get a breathable crib bumper or just not use one at all. I ended up with the breathable one for my second child (didn't use one for my first) b/c his arms and legs kept slipping between the slats and waking him up.
I hope that you haven't lost a child already, I truly cannot imagine the pain of it. Try not to stress too much about SIDS. It is so, so scary and sometimes our worries can get the best of us. Read as much as you can on the topic to keep yourself in the know and on the defensive, but remember the risk goes down dramatically when they can roll on their own and then again after 6 months...hang in there!!!