Say a Sparrowhawk and a Cirrus. Guess is the Cirrus will penetrate
better and hence be able to achieve longer flights in windy and / or
turbulent conditions?

Wow. Now THERE is an interesting question. How does a glider
with super stiff wings do going through turbulence vs. one
with flexing wings? I'd suspect the stiffer wings would
lose (they'd stall more cleanly instead of absorbing the impact)
but the difference may be too small to be important.

Any guesses on this one? This is pretty far out of my
field...