Do dynamic headset mics require a lot of gain (compared to condensor mics)?
Can you give a bit more description as to what your asking. I have used plenty of microphones in live environments and what they need gain wise is always dependent on the specific make and models. You can't just grab a shure and an audix whether both condensed or not and expect the same performance.
Condensers are typically more sensitive (Less gain needed) than dynamic mics but again that all depends on the specs of the mic.
Check out this article for the nerdy details.