#1: There's no battery in a PC. It's flash ram. We have NEVER, Not once, Zero times, Seen a power commander "lose" a map. This is dealing with hundreds of them a year.
#2: you will not get "10 more hp" out of a Yosh EMS box. The EMS does let you store multiple maps in memory, which is cool for racing as you can develop a rain racing map that detunes the bike and switch to it easily. However ... it does exactly the same thing as a power commander - allows you to lean or richen fuel delivery at any giver RPM and throttle postition (and the latest ones have the quick shifter, etc, like you can get for a PCIIIusb)
Dynojet beat them to market, had wider adoption, and pretty much no one buys the EMS stuff.