could not use Android File Transfer while Kies was installed. Simply dragging the app folder (Kies) to the trash won't fix the problem either. You have to download and run the Kies installer package but choose UNINSTALL when it starts and it will clean everything up for you. (I suppose there is an agent or two for Kies that is sitting out there.)
After that, AFT works great. (remember to bump up your device lock timeout though or it will disconnect on you if it locks during a transfer!