Its CheckRom Revolution HD ver 3.1.1. Flashed it 3 days ago and immediately reflash SpeedMod kernel S2-K2-K16 (I like SpeedMod for its stability and good battery performance). Since this is a no-wipe, I had flashed it without wipe or factory reset, which suits me well (although have all the necessary backups, you name it). Completely no problem at all.
However I did clear all caches, b4 flashing.
Typical experience so far, last 3 days:
Very smooth scrolling, good speed for application launch and the JKAY Deluxe is a real bonus
Performance wise, over the last 3 days:
Unplugged with 100% at 5:00am and within the 8 hours working time
Made average of 12 to 15 calls,
Average 8 to 10 SMSs (some days afew more).
Little tweaking on the phone, search mods in Kitchen pro (on 1st day) downloaded 2 items (camera and social hub) and installing.
Read gmails and company emails (can't remember how many but did stop and rest in between, numerous times)
At 1900hrs, battery still showed (during the 3 days) 48%, 52% and 65%. To me this is excellent and very reassuring.
I also believe the good performance comes largely to JuiceDefender Ultimate. When screen is off, phone slept rather peacefully. How I know this? Well, when phone is at 100%, I let it sleep. 1 hrs later, woke up the phone, still shows 100%
Perhaps it could go 2 hours but did not bother to try. SetCPU only 1 profile, screen off = 200/500
Oh btw, whislt phone is charging, I also noticed no traces of warmness on the phone. Could be the fan in the room?? Well! just thought this might be useful info.
I guess I have found the right combinations of setting, for now and will stick to this for awhile and use the S2 as what I had bought it for............a phone, with some clever features thrown in. Ought to stop the tweaking and flashing and just enjoy using this marvellous piece of invention. Hope the above info is useful to those who might need it, at some crucial decision making moment. Cheers!javascript:emoticon(':stars:')

Look into KitchenPro, removed samsung application, vlingo.

I noted in your post, that you had already done what devil94 mentioned ie setting > about > battery usage.
Now just tap on the top part of the display, where the graph is. You will get an expanded view of the graph.
Happy weekend.

If you are flashing to CheckRom Revolution HD 3.1.1, this is completely a no-wipe rom.
What I had personally done was wipe cache and Dalvik-Cache, then flash.
I have been on this rom for past 1 week now, no freeze up, no lock screen, no issue.
All my applications and data intact.
Have to re install Social Hub and other Samsung application (all the hubs) though, through KitchenPro (came installed with the rom) if you need them. Checkrom 3.1.1 removed all these applications.

This is my personal experience and hope it help.

Cheers!