definitely would take too long, was testing it last night.. I can leave it in color mode with lights out and when I turn on security lights it adjusts instantly.. but if I switch from b&w to color its gonna take a few seconds before u get a visible image again.
Gain Priority is an AutoExposure that prioritizes gain levels, in this case a low gain level.. gain == noise, so if you reduce the gain the image will get dimmer in exchange for detail.
I thought about scheduling it to run in color til midnight, then switch it to B&W when the security lights shut off.. but I think I'll get intrusion detection working well enough even w/the lights out (thanks to street lamp) that I can flip the lights durring activity as I planned.