Kicking and screaming, we have finally worn Ryan down and brought him into the 21st century
I'd go by what they^ said, anything Hyperion duo flavoured would kick ass, the 615 looks like it'll be more than enough for what you want to do. If you have apowersupply for your existing charger then ~200watts+ would be more than enough for the ~65watts per channel/lipo required by the duo charger.
Nice work on Robocain too, looking awesome so far