Well, I typically have the same exact usage on my phone everyday. Today, my dinc 2 has been used for more than my normal usage (very heavy) and I'm at 35%. It's 2pm and I took it off the charger at 7am, started using it at 7:30am
My dinc 1 would be dead by now with this extremely heavy usage. With skyraider it would be dead 30 minutes ago, if I was stock it would be dead like 2 hours ago (that's how much I've been using it today), and if I was on cm7 it would die just about now.
Of course these are just estimates, but like I said I typically have almost the exact same usage on my phone everyday, and I'm very familiar with the times the battery would be dead.