Can still remember before getting my first heated saddle thinking "is this a waste of money, seems foolish." But blew the extra hundred bucks to have Corbin do it heated. It's nice.
For longer rides in cold weather I'll go ahead and use the heated pants. For lesser distance or not quite so cold the easier to manage heated jacket liner and gloves together with the heated saddles are great though. It does make a difference further downstream. May be a placebo effect but I've convinced myself the legs stay warmer if the ass is heated. Guess it's the blood getting a jolt of heat before going down hill on that last trip before returning for an oxygenation and heating cycle.
Legs do get it last. Freshly juiced blood first goes to the heart, the brain, and the arms, then all the abdominal organs before finally going down to the legs. So every little bit of help a saddle can offer has to help. At least it seems that way to me.