Just simultaneously smoked a bowl of each in two different (but similarly chambered) pipes. To my unsophisticated tastes, they are very similar, but not the same.
The stockton is spicier and a little harsher. Otherwise, they look, feel, and behave the same. It could be age, a slightly different proportion of ingredients, or even a subtle topping.
In conclusion, different, and I like the 4th gen a little better. But probably not twice as much -in reference to the price-. I will happily sit on the stockton for a year or two and come back to it.
Even _if_ Mr. Stokkeybe just repackaged some old or non-conforming Mac Baren product to come up with this release, I wouldn't fault him for it. Stockton wasn't available in the states at the time and he is welcome to put his name on anything he feels worthy of it.