[Samsung Galaxy Nexus] JoeSyr:
Some thoughts:

Given that the "Android OS" report in battery usage was apparently subject to a major, but simple, calculation bug until 4.0.4, I have doubts about its validity as a measure in this kind of test. Are all of these ROMs using the 4.0.3 code as base, or are some backporting pieces of 4.0.4? Furthermore, how would you know if any devs sticking to the 4.0.3 source haven't gone in and fixed the bug themselves once it became known? If I had to guess just by looking at this, Gummynex, Liquid, and Revolution have this bug patched, the others do not. The similarity within and between these two groups is just too striking.

Even putting that aside, I'm not sure I see the sense in measuring anything but total drain, assuming your methodology filters out any variance due to usage habits (screen on, apps running, signal strength). If the phone is left to sleep and nothing else is running, shouldn't all the drain show the nature of that ROM?

Also, perhaps you can elaborate more on why not keeping the time constant seemed like an okay concession, because when the total drain only varies by 1 or 2% over 6-7 hours, I'm not sure how almost a full hour's difference across tests can be considered insignificant.

For example, compare AOKP vs Redemption in your results, redemption ends up looking marginally better. AOKP reads 4% over 7 hours, or ~.57% per hour. Without actually crunching all the numbers, 20 minutes of variance looks like enough to be significantly signficant if all we get for sigfigs is 1% increments.

With all that in mind, my general impression is that most of these roms are roughly the same for battery. I don't know if there is a feasible option to either get a full mAh reading, or to have program log the exact time a certain % level is reached, but both would give much more valuable data, I think.

Also, one of my first thoughts after looking at this was what kernels are these roms all using? It would be nice to see it included; are the devs using the stock AOSP kernels, stock with a few of their own patches, bundling their favorite custom kernel, or even developing their ROM with a specific kernel in mind? I know that liquid is bundled with leankernel, for example. It begs questions: Is there a good kernel complimenting a well designed ROM? A great kernel making up for a crappy ROM? An extraordinary ROM that shines despite a buggy kernel? (All example for conjecture). Hard to say without kernel as a constant across tests.

To summarize, my main critiques of your methodology are:

-Don't see the merits of using Android OS drain vs the total drain.

-Would like to see a standard time used in tests, or if possible, measure the exact time required for x% of drain, or mAh remaining after x hours.

-Would like to see a larger test range to establish statistical significance.

-Would like to see kernel as a constant, since anyone can flash their own custom kernel, and packaging one in a ROM may be a good move, but doesn't say much about the rom itself.

Those are my thoughts on the methodology and the results presented, but I would also like to express that it's very refreshing to see someone actually going to lengths to compile thought-out data on battery life, instead of the dreaded "wow great battery life awesome ROM" posts that litter the ROM threads.

Edit: As far as a more precise reading goes, if you run better battery stats, Menu->More->History->Menu->View Serie gives quick access to a log that I think would be helpful here. I'm not sure what triggers the program to write to this log, but it's pretty well populated regardless. So you could decide you want to drain the battery to x%, and just read off the first time the log shows that level.