Well I have been googling, and the statments in those videos are no smoke when running, power is good, 3 minutes on gas to warm it all up and cut off gas, and switch to gasification.
The smoke is just when they are starting the fire in the gasifier, which with the proper setup would only take a few minutes. I was concerned about that too, but while driving theres no smoke. Statements made also that its more efficient as well.
MotherEarth website did a video on Wayne Keiths setup from Alabama, its very interesting. He has several trucks. I wondered as well about the power, but to get from point A to point B on wood is great. A chord of wood = 5000 miles.
I will study up on it more, the cold Alberta weather might hinder the operation as well, especially the radiator part of it all. The only by product is fine ash at the bottom of the gasifier, which can be used as fertilizer.