I have a Milwaukee heated vest and love it.
I can work in an unheated shop and not feel cold.
Below zero weather is bearable for hours with this thing. My first one wore out last year and I replaced it with another. Absolutely love it. Its actually a well made warm and comfortable vest even without the battery.
Have a Milwaukee and love it but haven’t used it with the sled. Bought it for my bike. Went with Milwaukee since I have a bunch of the tools and thus batteries. Can hard wire it in pretty easy too with some adapters and cords.
I have the power wire for my vest but I've only used it one time.
Never used mine for the sled either. Just for working in the shop or outside.
I think I'd sweat to death with it on the sled.
I only wear a jersey, tekvest and an uninsulated shell on the sled.
My son's got me a heated Snap-on coat for Christmas a number of years ago. It uses a battery to work. It works very well in our cold temps of 30 to 50 below.