No, the ECU flash will take care of anything a Power Commander would offer you. Plus, the Power Commander is an additional point of failure on the bike. Also, unless you have some idea about tuning an engine, you probably will waste time fiddling with it and not really getting any benefit.
I'm not really trying to talk you out of it. I knew the disadvantages and I still bought a Power Commander with an Autotune module. The one major benefit my setup has is it give me control over the fuel system, so I can do things like fix my loud backfire pop on deceleration myself without any hassles.
One big advantage to the Power Commander are the modules you can install, such as the Autotune, the LCD data screen, quick shifter, ignition module. etc... but it can get expensive.