[shaggylive]

yea, it depends greatly on coverage and amount of email, talking, txting.
if you have an evdo signal you get better battery, but talking and sms constantly switch to 1x, and the ratcheting kills watts. so if you don't use the data much (other than email) your better off setting to 1x only. then it will depend only on your signal and how much mail you get.
but... (there's always a few.... lol, nothings perfect.... yet.)
active 1x data will block calls and send them strait to v/m (another reason sprint needs to offer visual voicemail)

I actually have mine set to manual with a script to sync in the morning, and the email I care about is also set up with imap, checking every hour.