That's funny. I had a meeting with a senior Moto guy a month ago and he was saying they were hoping they could get more than 10 hours of battery life. I didn't even bother posting it because it was an off-hand comment and frankly, unbelievable. I met with him again this week and he said the battery life would be "moderately better", so way toned down, but maybe so close to launch he didn't want to leak how good it was going to be.
He did say there is going to be an update to the networks in early 2012 that will make it easier for the LTE modem to turn off and on, and that will help everyone's LTE battery life.
FWIW, in the last update for my Thunderbolt, a very easy LTE on/ off switch was added. When I first got the phone during launch week, there was no such option and in order to switch between LTE/CDMA and CDMA only you had to download an app.
Now, it couldn't be easier. Just flip a switch in the wireless settings, and I go from LTE to CDMA in like 10 seconds (and vice versa). Staying in 3G really helps the battery life, and if I want to stream netflix or download an app or whatever, I can switch almost instantaneously to 4G.