I was thinking more of a bicycle type helmet so it doesn't screw up your hearing.

I've come in contact with both round and square booms (thankfully at relatively low speeds) and they feel about the same. Kind of like getting hit with a baseball bat vs. a 2x4. You tell me if you can feel the difference

Given all the things you can hit with your noggin as you tinkerbell toward the foresaty, what type of helmet would offer the best compromise of protection vs. ease of use?