Which is more reliable?

Does the six speed get better MPG's?

 

I know the 6 gets better MPG (combined with the 6.2L motor).

I believe the 4 is more reliable... but don't quote me on that.

 

4's have been around for an eternity where as the 6's have only come to the regular consumer market more recently. Sure the higher end car companies offered them earlier than say GM for example but they are still fairly new. You would imagine the 4's to be beafier since they're not cramming all the gears, valves, etc for 2 more gears into the tranny case.