Coming in late to this...
Wife and like the heated mattress pad we got got front Bed, Bath and Beyond. Works great. Mostly use it to warm bed before going to bed. Between that and flannel bedding from LL.Bean, it works out really nice!
I do have a very bad family experience. I have a cousin who is blind, and quadriplegic. His care taker had got him in bed, and had an electric blanket on him. In the night, it caught fire. Not bad, and was quickly put out. Well, not bad for someone who could help himself.... My cousin could not, and sustained burns on his legs. Ended up requiring amputation...
It took a long recovery, and time off work. For being blind and quadriplegic, my cousin for years had a local daily radio show... He did eventually recover, and got back to work.
I would definitely advocate the liberal use of smoke and CO2 detectors in these cases.