The ear pieces aren't a backup; they're required for the TSO. If you order the headset with the mic, it can be ordered TSO's with the stickers and document. If you already have a headset and just order the Uflymic, you need to send everything to uflymic to get the TSO stickers.

I had the mic and the headset before the TSO was offered: I sent everything back to uflymic and had the TSO applied. They didn't have it for long, and it returned with a paper describing the TSO, and stickers on the mic and headset.

Technically the earbuds are required to be used for the headset to be fully TSO'd, as they're part of the TSO because the headset goes dead when the battery dies. I found that the battery would last about 50 hours of flying, and I had ten hours of time or so with a flashing light advising the battery needed changing; I always changed it preemptively and carried extra batteries, so it was never an issue.