The difference in movement speeds between weapon up (non tactical pace), weapon down (double CTRL) are barely noticeable, worse is that the tactical pace with weapon down is only 2 seconds slower.

The speed really harms the final animation since the arm moves in an uncanny way, when we first saw them in the Stratis Teaser the speed was perfect or near perfect http://www.youtube.com/watch?v=DXIoEUq8YE8 right now they are far too fast.