Does force closing apps have any benefit on iOS devices?
There's been much debate and discussion around this topic.  I believe it was beneficial for iOS back in the v3 and v4 days but now it's not.

Craig Federighi even came out recently saying it's not necessary and it doesn't increase the battery life.  Apple has built-in their memory management the proper time to suspend and/or kill an app when necesssary.  The only time you should force-close an app is if it has become unresponsive.