Ive never done the experiment myself but in nature flowering plants receive more red spectrum light (2700k). I would bet that it makes a difference for sure. The amount of difference is hard for me to say. Are you talking about cfl's the whole way?
i've heard of hps/2700k cfl from the start all the way through flower but never the other way around. not exactly sure. CFLs arent too expensive, i would suggest you just make the investment! Goodluck!