I've also found some value in conscious use of what would be considered my "shadow" functions. I agree that the psychological reward is so tightly constrained to not be as pleasing and instinctive as the reward from using preferred functions... but there has definitely been very quantified reward, which in turn can be psychological pleasing.
For example, I can feel very good after making a plan, being proactive, and numbercrunching through the quantified steps I've laid out for myself (Te'ing). The thing is that, regardless of how happy I am at having finished the task and accomplished my goal, I don't feel particularly motivated to approach things that way. Regardless of reward, I still loathe having to do it, and I do it only out of necessity.