The ear buds are part of the TSO I dont' wear them, however. I carry them and if there's an issue, I can put them in. I see them as more of a back-up in the event that I lose my audio and cant' get a replacement somewhere. Otherwise, they stay in the little case.
If you want them to be more comfortable, you can always take them to a hearing-aid shop of other facility that can make ear-molds for them. They won't need to be jammed in your ear, and you can comfortably wear them for extended periods.
With most aircraft ANR sets, when the battery dies, you lose ANR but not audio. With the Bose/UFM, you lose all audio. And it's not just the battery... failure of the circuitry in the Bose will kill audio as well.
If I am wrong, I'd be happy to be corrected. The Bose/UFM is a nice setup.
It's an excellent set-up.
With the QC-15 and the U-fly-mic, loss of battery power means loss of the hearing portion of the headset if one is not using the ear buds. That's the reason for the TSO requirements to have the ear buds.
I've used the QC-15/UFM setup quite bit, often on long legs that last between 7 and 12 hours, and it's held up extremely well. I've found that a single AAA battery lasts about 50 or more hours. My policy has always been to replace the battery at the first sign of it starting to blink. It goes about ten hours while blinking, so there's plenty of leeway.
If one has the ear buds in, then the mic and the audio are uninterrupted in the event of a dead batter. In that case, all you lose is ANR.
I used the ear bud plug in to hook up an MP3 player. On long oceanic legs or flights cross Africa and other desolate places, music can be a real God-send. It makes the time go by more quickly and I think it tends to reduce fatigue a bit, keep the mind refreshed, and keeps one a little more focused.
The only problem I ever experienced with my headset was a decline in the ANR, with more noise, and that was a function of the ear seals eventually deteriorating. I replaced the ear seals and fixed the problem.