It's not any one component that's producing the effect you're describing -- it's a synergistic effect. Also, I believe the VAs in the Frog series are subjected to a cavendish process that helps produce the body you describe. The latakia used is also a cool, smoky, and smooth leaf -- delicious stuff. The perique in FMOTB is barely noticeable to me, but I like blends where the perique is HEAVILY applied.
All of the Frog Morton blends are delicious, and all of them have that "liquid smoke" characteristic you describe. I don't smoke them much because they are so mild, but I do think they are examplary blends and recommend them to others. I like blends with a lot of strength to them, and the Frogs are probably the mildest latakia blends on the market. Which, of course, makes them ideal for folks who are just starting to get into latakia.
And yes -- I think Shortcut to Mushrooms would be right up your alley. BUT I would even more highly recommend "Northwoods" by Boswell's. It's a lot like Frog Morton on steroids -- more flavor, more nicotine, more body.