I know this is an old thread, but this method works for vegging plants, cannabis being no exception. Currently, Twelve12 and Siscokid on the forums here are doing this very veg cycle (I'm sure others as well).
I read a recent article about this in a Cannabis related print magazine, and the author not only experienced significant $$ savings, but also found the plants thrived under this lighting routine. The article was very well written in that it laid out substantial energy savings over time.
Commercial growers of other flowering plants have been doing this for a long time, and if you think a dozen roses is expensive -- you wouldn't believe what they'd cost if they used the same ridiculously wasteful veg light cycle we use typically for cannabis.
I've seen enough now from members of this site, and literature I've read in several places to be confident this works. If you look and study up enough, this isn't a matter of opinion - it's hard fact. I'm afraid those who are scoffing or unwilling to try it are doing so at their own expense. Literally!
Don't get me wrong - our medicine is valuable and I understand unwillingness to change and the potential for problems people are concerned with, but I have become convinced. I wish the article I read were available online - it was a real eye opener. If anyone wants to PM me about it, I'm happy to give more info as to what print magazine it was in.
Just my 2 cents - can't wait to try this when I'm vegging again.