I was using the RAZR M, just switched to the HD Maxx. I really haven't put the phone through more than a couple hours of use. I took it off the charger yesterday after being fully charged and 14 hours later (no use, overnight) I had 99% battery. My M would be at 85%. I really like the M, one of the best cell phones I had but the signal on the HD is much better which is why I bought it.
What worked for me in getting great battery life from my M: Go into Google Maps, settings and turn off location reporting from this phone. It virtually doubled my battery life on the M where I'm get 14 hours with 90 minutes of talk time and still have 30% battery.
Also, I use a profile manager with a widget where I can set my phone to airplane mode. Generally before I jump on the subway, I put it in airplane mode for 15 minutes. Same if I'm working where there is no cell service.
I'd like to see Motorola have a smart action that would stop the phone hunting for 4G when the signal is weak and put the phone into no mobile data when it is on 1x for fixed times, say 10 minutes then check signal again.