Data Usage Concerns for 5S - Should I return before I open?

TheGuyUpNorth

My daughters iPhone 4S is on an unlimited plan, and she usually never exceeds 1.5 gb per month.  Based on hundreds of post on this site, and others, it seems that iOS users who make the 4G LTE leap are being burned with excessive data usage.  I took her upgrade and accepted the 2g cap based on the fact that she has really never had an issue.  It would appear that I should either returns the 5S or pony up the difference and pay full price to keep unlimited.  Any advice would be appreciated.

Tidbits

Phones are doing more and more. Simply moving to faster speeds often apps will use more data because polling happens in quicker intervals as things take shorter to download.

For example on LTE something takes 1 second to poll the data. On 3G it takes 10 seconds. Let's say at the end of the download the timer for a repoll happens(5 minutes). On LTE it'll poll more times per day.

This is why I like to use apps that I can change when it polls. Usually I set them to when I open it rather than X time.