[HTC One S] Rapier:
Battery drain it's tricky and in many cases the culprit was an app or service running not necessary the ROM or kernel. Install a battery monitoring app like GSAM Battery or Better Battery Widget and find out what's eating yours.

Many people don't pay too much attention to certain details when setting up the ROM and apps and are facing battery drain later. Some are posting screenshots with 1 day or longer battery life and all say "WOW, how could you reach that, I am barely getting ...whatever". Those 1 or 2 days of battery life can be achieved with a low usage of the phone (that is almost no calls, not too much screen on time), BT, GPS, mobile data or Google Location services switched off, no Google Now, no automatic brightness (brightness set to manual and at a low setting), not to mention added apps like Greenify. Also the OC, gov and scheduler matters as well as the signal coverage (lower signal areas drain more battery).

So as you see, battery drain depends on very many subjective factors and most of all on how you use your phone. I usually get 4-5 hrs of call time and have 2-3 hours of display-on time during one day...and I don't have the battery lasts for one day. This is normal and you shouldn't expect to use your phone heavy or moderate and get 1 day + battery life cause you won't.

Now some will argue and say ... "But with that ROM (or kernel) I am getting more...". Well, go use that ROM (or kernel) then...oh, you'll say "But it's not so pretty, or doesn't have too much customization or it doesn't work so smooth". My friends, customization features, smoothness, performance will ALWAYS come with a price...and in most cases it's battery drain. You cannot have both. I know you would like that, I am too, but everyone should make a compromise between those two. In my case for ex, if I like a ROM, how it works and what customization capabilities or options it has, I don't care too much about battery life because I'm a heavy user and anyhow my battery won't last a whole day. More than that, I have wall charger, USB cable to my laptop and car charger. Almost everywhere I can charge it so what I need is to have the battery lasts till I reach a charging place for me. So I do care more about the ROM and how it performs. Now on the other hand, if you're one that want to have battery lasts a full day cause you don't have a charger nearby, you must sacrifice some of the performance or smoothness or stop using some of your battery drain apps (stop automatic sync, background sync, mobile data, GPS and so on)

Sorry for the long post but I saw alot of questions related to battery drain (more or less real) and I noticed that people are getting higher expectations without reason. No one is a wizard and no one could makes miracles. Except for the case that you really have a defective battery, all phones would behave similar in identical conditions. If you don't get the same battery life as somebody else, it is you (or your apps) that makes the difference...not the ROM nor the kernel

I remember a joke about someone who was asking for a speed limiter for his car...the answer was "Try to push less on your throttle pedal..."

My 2 cents...