I have them fitted and can say that heated seats are crap.
You will no longer freeze on cold morning/evening drives.
If you have a sore back you will no longer be able to whine because it will feel better.
And at the Nationals, when it is blowing a gale and trying to rain, you will have to just sit in your car feeling warm and smug knowing that your mates are freezing.
No idea of why anyone would want them...
BTW you want both the seat and back