Hi,
None of the bad things you list will happen if during transition you lower the light during the transition. When I get out of town for a week or two I just shut off the lights and the CO2 and when I return I resume the CO2 with half lights for a few days without issue. Light and Carbon consumption are directly linked so as long as you don't overdrive the system with lights you'll be OK whichever direction you go.

Cheers,