Rolling down hill

depends what's at the bottom of the hill. if there's a stop sign, then gentle braking all the way down to come to a stop at the sign would be better than gliding down, picking up speed, and then having to brake hard (maxing out regen capabilities) at the stop sign.
if at the bottom of the downgrade is an upgrade, then don't brake at all, and apply a tiny amount of throttle to cancel the natural regen.
if at the bottom of the hill is a flat stretch, then glide without regen, unless you need to regen a little to control your speed, but keep your speed as high as the limit/situation allows.

 

For me a simple down hill on an overpass would regen to 7 bars most of the time at a speed from 50 down to 35.

 

The bigger question is why do you want regen? A low SOC is not necessarily a bad thing. Unless you have to stop at the bottom, it is more efficient to bank the energy as momentum than to put it into the battery; in other words, gliding is more efficient than regenerative braking.

To answer your original question, braking will produce more regeneration.

Tom