I just set up Juice Defender today, on the Aggressive profile. It's been a very light use day, but after nearly 10 hours on battery I'm at 84%. The main factor is that the WiFi isn't on all the time, only for about a minute each half hour to allow email and weather widgets to sync, and when the screen is on.
My other two modes of operation are in the car, where I have Bluetooth connected constantly, and away from both home and car. I'll have to see how Juice Defender handles those situations and how I should modify it. I know Bluetooth can drain a phone. My old RAZR phone went from fully charged to near zero just being in the car connected to Bluetooth on a 5 hour drive to New England. That's when I learned I needed a car charger and needed to keep the phone on it. That may prove to be the case here, too, but we'll see.