It was scary using one the first time. The chicks tend to be so content that they are quiet. I was not used to quiet chicks.
That was my experience as well the first time I used a heating plate as well - it was soooo much quieter (with much less jostling/complaining searching for the "perfect" spot) and it was clear that the chicks were much happier, but I was constantly picking it up and looking under to make sure everyone was okay.