It might extend your flower time, depending on how much you stress them. If it's 12/12 from seed, I'd leave them alone and grow one big fat cola on each plant. Higher growroom density, IMO. Del6666 grows colas as thick as footballs, I'm amazed at what can be done in 12/12 grows.
I've said it before and I'll say it again (LOL)....
At the Equator, all day/night is 12/12....and I understand that some outstanding weed is grown there. We shouldn't look at this as some kind of light manipulation, but as how things really are in some areas of the globe.
I bent my girls over when they started getting too tall while they were in bloom, with no ill effects whatsoever. The next day, the buds were already starting to point back up at the light. So no isues at all. I used wire hangers straightened out with hooks at each end to bend them over. Just be gentle, you don't want to snap them.