This is what I was saying; for light use on short trips in moderate temperatures, I would rather the convenience of grips and seats. But for longer trips, and especially if the temps are going to be in the 30's or below, then the clothing is better by far. So just have to decide what your riding style and conditions are. I see where the 2-up heated seat option is $300, so it is a pretty significant investment.
I just re-read the OP's actual question… does a heated seat make a difference if you are feeling the chill through your gear. I take that as ALL your gear… as in, "my core, arms, legs, hands, neck, feet, etc. or some portion of all of this is cold." The answer for me is NO. You might get a hot spot on your butt, but this is not going to carry to the rest of your body. The only thing that helps in that regard is a better, breathable wind blocking layer, heated clothing, or taking a warm break.
The heated seat on my ADV bike didn't do much good, but laying on the tank and putting my hands on the engine was pretty good. That bike had heated seat and grips. Didn't help me at all in 33F weather at 70mph.