Ken,
I have heated seats fitted to my cooper and I seriously recommend them if you are having leather seats as they do get very cold, especially at the
mo and the seats heat up wuicker than the climate control so they help warm you up!!! If you're not having leather then maybe they really are a luxury! but in terms of them getting too hot, they don't. They warm up to a nice temp and then they ease off and warm up again once the seat temperature has cooled.
Jon