The Shearwater Petrel 3 Fischer Computer-controller (now available from Dive Rite) combined with a HUD is the best Optima-CM configuration for me because it:
1. Is the safest configuration. Most of the CCR fatalities I have reviewed were caused by breathing toxic PPO2. Tunnel vision (intense focus on a visual stimuli that results in screening out of peripheral sights and sounds), hyperfocus, (complete absorption in a task, to a point where a person appears to completely ignore or tune out everything else), narcosis, stress, or even fatigue, may lessen the effect of flashing red numbers and audio warnings indicating problems. The Petrel 3 adds, all but impossible to ignore, strong vibration warning alerts to its usual red flashing warnings. The HUD remains a redundant visual alert/information system.
2. Allows for the display of four gas pressures on the controller and allows for easier programming than the NERD and makes system information readily available and changeable, to other divers. I have not dived a NERD, but I enjoyed having the HUD’s light signals in my peripheral vision. For me providing the information in a different format than the controller, keeps me aware and vigilant. Or perhaps I’m just too cheap to buy a NERD.
May all your dives have the surfaces you planned.