i agree try the free version of JD first just to make sure you can get used to it. i used it for a little while and noticed that my battery did last longer. my cousin uses it on his evo and said he has noticed a big improvement in his battery life and no longer wants to get an extended battery.
i switched to widgetsoid and just turn off what im not using myself so i can easily turn it back on if needed. like bluetooth, gps, wifi etc. with JD depending on what profile you use it automatically shuts things down to preserve battery life and i would have to disable JD to turn them back on.