[letsgoflyers81]

This is push, but it's IMAP with IDLE which is different than Exchange. I can't comment on which has better battery life because I haven't done much testing. But look at it this way. If you set your device to look for mail every hour and you actually receive mail every 10 minutes, then push will use more battery life because it'll connect and download every 10 minutes instead of once an hour. But if you have your phone set to download every 10 minutes and you only get mail once an hour, then push will save battery life because it's not connecting every 10 minutes when there isn't any mail.