If you have a short downhill then yes, it is better to lightly use the brakes to charge the battery without wasting any kinetic energy spinning the ICE.

The "B" mode automatically uses the maximum regenerative braking force combined with spinning the ICE. At the top of the hill the engine RPMs are low but once the battery fills up, and it does so quickly going down a hill, the electric motors can no longer be used to provide braking force. At this point the engine revs very high to make up the additional braking force. I was under the impression that when providing engine braking the ICE is being spun but is not being provided with fuel.