I tried, but so far I made only ONE boundary along the ground.
So actually it's not a choice; if I want runs I have to wait for bad bowling and for arial route.
And I've got to tell you. Hitting sixes isn't a joke in hard mode. You have to time really well. A bit early and you will give a catch to a fielder.
When I first time changed from medium to hard my team went out for just 90, where I instead could hit 150-250 runs in ten overs in medium mode.
So in hitting sixes, there is indeed a big risk. And that's challening enough for me.