Originally Posted by memoreks
While I haven't got proper metrics to back it up (I have a day job!), I haven't found the battery life of 4.0.4 with the 700mhz fix applied, to be any different to 4.0.2 battery life.
As a rough guide, my GNexus with a 4.0.4 ROM and the "700mhz fix" applied has lost on average 2.4% per hour today, with 3-4 phone calls and a bit of light usage. This is kind of what I expect from a modern smartphone without going crazy on custom kernels etc.
If anyone has the spare time, then it would be interesting to compare battery utilisation between a working 4.0.2 and a fixed 4.0.4 installation, and see if the 700mhz increase makes much difference. My guess is that it won't.
I think you're broadly right, that 4.0.4 with the 700MHz "fix" probably behaves similarly to 4.0.2.
If your GNexus is disconnecting from the GSM network for long periods of time with an unfixed 4.0.4 ROM, then its bound to improve battery life as it is not keeping in contact with a cellular base station, and is powering down the relevant radio parts of the phone.
In my experience, this isn't true. The constant attempts to re-establish the signal actually prevent the phone from going to sleep at all. I rebooted my phone half an hour ago and it has probably one minute of screen on-time since then, but it's been awake 95% of that time due to the constant disconnections and attempts to reestablish the network link. Battery life is plummeting like a stone as a result - 6-7% in half an hour.
I believe the 4.0.4 update has enabled some more aggressive power saving techniques (smartreflex) that weren't used in 4.0.2. This is resulting in greatly improved battery life for most people. Unfortunately, on certain devices (such as ours), it's proving to be problematic.
Clearly it needs a fix from Google - I just hope the fix results in us getting the same power savings everybody else does, and doesn't leave us out in the cold by simply turning off the feature.
I've submitted my log and starred the bug report.