I run ATK as soon as the phone starts up, kill everything including ATK.. I see no difference in the phone's speed, but the battery does last longer, and on a G1 that is important. All my text messages and e-mails get through fine, but once one comes through I run ATK and kill everything again.
Even with ATK at times I find my Google maps app will at times start itself and drain my battery. Not sure what that is about.