Everything about Tennessee Whiskey is the same as Bourbon except for the Lincoln County Process (ie, filtering the white dog -- new-make spirit -- through sugar maple charcoal prior to barreling it). The mashbill is the same kind that you would find in a Bourbon, the distillation is identical, the barrels are identical. It's just the Lincoln County Process that is different. And it makes a tremendous difference. Every Tennessee Whiskey that I've ever had -- Jack Daniel's Black Label, George Dickel No. 8, George Dickel No. 12, and Jack Daniel's Single Barrel -- has had a distinctive sooty aroma and flavor. It has to be the Lincoln County Process that creates this characteristic. And yet that makes no sense to me. The spirit spends a few days filtering through the charcoal. It spends several years inside a charred oak barrel. One would expect that effect of the char from the barrels would swamp the effect of the charcoal, but it doesn't.
Anyway, JD Single Barrel remains an excellent whiskey. It's got the distinctive Tennessee Whiskey sootiness and a whole lot more. It's not cheap, but it's not a bad value.