There is a third option. Bow arm straight but NOT locked. This is what I recommend. I feel that with a bent arm, you need to hold the whole weight of the bow with your muscles and IF you lock the joint, there is no "give" or shock absorber effect available. Nature gave us the ability to "lock" certain joints for the ultimate strength we are capable of producing. When we use that "locking" feature, we are essentially saying, "I'm willing to sacrifice that joint to what ever task I am trying to accomplish at that moment."
Can you do it with bent arm or locked joints? OF COURSE you can, BUT....
Arne