Matt, reference the Bf4 thread, could i ask what you use to record Mantle footage with please bud?
Yes sorry mate missed your reply. Currently im using Mirillis Action, however it has a performance hit and you have use borderless window mode, which also has a performance hit.
I'm guessing you can't use GameDVR with Mantle yet? If so Mirillis or something similar is your only option.