Fresh thoughts following the assembly of the machine. I really regret for not adding the arm to my shopping list. I would say it should be a part of a minimum setup, otherwise good luck finding a good place to the monitor and the rest of input devices. Buying it now isn't an option - the shipping costs more than the arm itself, so I'm definitely going to add it to my next big shopping with Tormach.
The Tormach product seemed overpriced so homebrew arms to attach the monitor+keyboard and another to support a tray of TTS holders were my first projects when I got my 770. Making your own doesn't require a lot of material and will provide valuable experience with CAD/ CAM/ workholding/ etc.