true--stiffer stem seems to give more power transfer/responsiveness,
especially when climbing.

Stiffer seatpost does make the ride a little bit more harsh. I think
a nominal increase in power transfer occurs because the seatpost
is one less thing that flexes quite as much--so slightly more kinetic
energy goes to the wheels. The general idea is that
all kinetic energy that gets spent flexing metal is not transferred to the road.
Not that any of this matters in my case
except for the purpose of having fun.