Nope, never been on IB.
Certainly, I would love infinite battery life, and have to admit that one of the biggest reasons I maintain a lounge membership is to be able to find a plug to recharge during layover, I'm just saying it's not worth much $, luggage space, or weight to me to have longer battery life than what it does now.
Wifi certainly does suck the life out of the battery. The other thing to check is that you're not keeping all the apps open all the time - you have to bring up the tray and actually close them out separately, or they're still open suckin' juice.