Earlier this week, I uninstalled JuiceDefender because it often kept my APN off even after I turned on the screen. Remarkably, my battery improved notably. I work a very regular schedule, so I get medium usage 9a-10a, low usage 10a-6p, and high usage 6p-10p.
With JD running (Monday, Tuesday), I would be at 40% at 10 pm. Without JD (Wednesday, Thursday), I was at 60 or 70%.
To be honest, I'm disappointed. JD seems like such a cool idea. I'm also generally skeptical of people who say that an individual background app can drain this much battery. But that's how it goes!
I run BB v.4 with Chevy's 800 MHz. YMMV.