first off, how is the battery life on these things? is it a true 15 hrs.? i like the idea of the upcoming xp400 & xp300 being rechargable, but then you lack the customizable presets or surround sound features of the xp500. this leads me to my second question. do you think the xp500 headset will drop in price around the time the xp400 & xp300 are release in march?