I do like the point that a poorly driven stick might get worse gas mileage than an automatic. I've never driven a stick, so it will be new to me, and I won't be the smoothest stick driver for a while.
However, I do want to be able to do most any work my truck requires. A 6 with a manual transmission seems like the simplest system. That would be worth a lot to me, and still, that setup seems like the best mpg in the stock setup. So I think a medium to large I6 with a stick is still my goal.
However, if I see a cheap V8 truck where everything else is perfect, maybe I should jump on it and consider switching out the rear later on.
So much to learn...