Sooooo..... take 3 hours out of the morning and 3 out of the evening? Ummm, yes. That would be more like the natural light cycle anyway as the day's get shorter the sun comes up later and goes down earlier.

I have my flower run overnight (7pm-7am) and my vege in the day (5am-11pm), so when I move a plant it gets an extended light cycle.

As long as the change is made and your not waffling back and forth on the light cycle for an extended period of time you'll be just fine