I have been using the Mega Atty with both riva and ego xl battery since August 2010 and can tell you that the battery will last upto 12 hours depending on how often you vape. No leaking problems here. Just becarefull not to overflow the 2ml cart.
My first atty, went out a few days ago which is approx 5+ months. NOT complaining!
I had reserve and just got my LR mega atties in... I can tell you so far that the battery lasts about 1 to 2 hours less then standard resistance atty.