Anyone who relies on services that require constant EVDO connection shouldn't use these apps. Gmail, exchange push, google talk, mms messaging ... those services need a constant connection for real time to work. With that said, I don't use them because I'm a crazy heavy GTalk user.
But this phone has a paired down version of JD/green power built in. The battery saver profile turns off the 3G radio after a defined period of inactivity. Unfortunately there's no option to have it wake and sync at intervals. On the plus side it leaves data on for 15 min after last activity so if your waiting on a GTalk response the person has time to send.
I've played with JD pro, green power, and motos native offering and, this is just my personal experience so judge for yourself, any savings were negligible at best and just weren't worth the impact to services I use and love like GTalk.