I would say go ahead and switch em I just put mine into 12/12 2 days ago and have had all my 16x 23w 2700k cfl the day of the switch and usually do change bulbs the day of switch
I wouldn't worry bout the stretching too bad ur gonna have sum flowering stretch regardless and if it hasn't stretched under smaller 125 then should be fine just keep it close as possible cfl are not great at light penetrating canopy so the closer the better!
Good luck