The X-11'S seem to fit me a bit better than the Bose. What I really like about them is that they pack down so small. I get 25-30 hours out of mine (2500 Miah rechargeable).

I was having a similar problem when I was instructing in Skyhawks in winter. I found that when the battery pack was resting on the floor in a cold soaked aircraft, the batteries would get cold fast and drain quickly. The problem was fixed, when I made it a point to keep the battery pack off the floor. In the summer, it didn't seem to matter but in the winter, the floor of some aircraft never seems to warm up. Of course, If you're in an RJ, I imagine the floor stay warmer than a Skyhawk.

I also found the aircraft to be a big factor in battery life. When I was flying skyhawks, I got 15-20 hours of life. In the Saab, I get 25-30. I imagine the quieter the plane, the longer the battery life.