When I last used CM7 (probably back on nightly 153 or so) I also used Chad's latest kernel (i think its posted on the OP for the CM7 thread). My battery life was outstanding.
With Nils' Business Gingersense 3.0 v1.6, battery life is not as good. I'm not running any special kernel. I've got a 1750mh battery and I can usually make it through a day with no problems but if I've got a looong day, like off the charger at 0600, I'm typically looking for a place to get some juice by 7pm. Obviously your mileage will vary. I'm not a power user, just the typical emails, texts, phone calls, some surfing (gotta check my Android Central!), Facebook (I know, I'm a loser), Slacker Radio or my built in music player for a while, and some Angry Birds.
Long story short, CM7 will most likely get you better battery life. The Sense UI in and of itself is kind of a battery hog.
I'm sure I'll go back to CM7 at some point but battery life isn't really my main drive in life. If it is yours you may want to go with CM7 and Chads.
Hope this helps!