If I were doing domestic LE work walking in and out of ambient light or using visible white/conjunction with others who are I would prefer single tube. No blackout issues/auto shutoff and ability to use dominant eye through a red dot looking into a bright house or for pistol work. I have had experience with not being able to flip up NOD's quickly enough, you would have more difficulty getting them off quickly if they were just on a head harness, at least the ones I've used. Dual tube is great if everything is blacked out IMHO but, my experience with dual tube is limited. Glad the deputy had a set NVG's, I think they are awesome and I'd love to see domestic LE end up with them in patrol units. Your SA is much better when you can see and given the regular ambushes we are seeing on LE when responding to domestic and some fake calls for service it could truly save some lives.