Going to a real issue in the AOKP versus Sense ROM battle (i.e. Episode VII)
With AOKP ROM's, both ICS and JellyBean, on the HTC Desire HD I noticed that if you check the battery history stats, AOKP ROM's have a lot of awake time even when the screen is off.
With an ICS ROM on a DHD or a AOSP ICS/JB ROM on a Galaxy Nexus (stock), the readings for awake and screen on is almost identical. You will find short burst of awake activity intermittently even when the screen is off background apps update.
With AOKP ICS or JB on the DHD, it seems that it takes a more time for the ROM from going from screen on (or awake with screen off) to sleep mode.
My best guess with battery life is:
a) During long periods of inactivity the difference in battery use should be negligible (based on testing consumption when left on overnight while I sleep).
b) During heavy use, I think the AOKP ROM seems as efficient (based on testing consumption when playing a game).
c) If use during the day is frequent but short periods of activity, for example, if you check your phone for 5-10 minutes every hour or so, the AOKP ROM is not as battery efficient since it spends a substantially longer period of time awake even after you turn off the display.
My best guess for the reason is the hardware drivers. The OS is open source, but the drivers are not. So a Sense ICS ROM uses HTC proprietary drivers while a AOKP ICS will use open source drivers.
A solution to removing bloat and keep HTC drivers might be to de-Sense a HTC Sense ROM.
One caveat with my observations
When I install an Sense based ROM I freeze/disabled the following apps:
HTC Location and widgets
HTC Premium Navigation
HTC Hub
HTC Like and widgets
HTC Watch and widgets
HTC Stocks and widgets
Some unused HTC widgets (i.e. Calculator)
Things I don't use like Dock Mode and Media Link
Stock apps I don't use Email app (Since I only use gmail anyway)
In that Sense I am comparing a Sense "Lite" with AOKP.