I've often wondered how much difference a heated seat makes. I thought maybe not much since we are dressed for the cold anyway but I've seen several folks indicate, like you, that it makes a big difference riding in cold weather. Might have to add this to my wish list.
Do you mind saying how much it costs and how long they had your seat?
The way they work they make an appointment with you for your seat. You ship it to them to arrive the day before the appointment and they do the seat in One day and ship it back.
I was without my seat a total of one week...all but one day was transit time.
Their web-site is www.meancitycycles.com
all their prices are listed....Very reasonably priced work is excellent.