Let me give you a real world analogy about Push vs Fetch. Most people are still not clear about this.
Imagine you own a P.O. Box at the local UPS Store.
Push: When mail arrives UPS calls you to let you know that there is mail in your box.
Fetch: When mail arrives UPS tells you nothing. You have to drive to the store and check for yourself to see if you have mail.
Which one is better?
It really depends how much mail you get honestly.
If you constantly get e-mails Push would keep your phone awake all the time to inform you that mail has arrived and eat at your battery.
If you set a fetch schedule for once an hour, it would only wake up once an hour.
If you are in in a position where how quickly you see an e-mail is critical to you than push is the better option because if a mail arrives AFTER the 1 hour fetch you have to wait another hour to be notified.
Push. That's my primary reason for having a "smart" phone to begin with. And it's one of the reasons why I'm not happy with my iPhone. The Apple push mail support remains unreliable. Nothing like Blackberry used to be.
Sometimes it works like a charm - sometimes it doesn't. Which to me is proof that it's not a settings issue or any of that. Something along the lines of how the push mail service communicates via the iPhone is whacky.