It can but would cause more stress then its worth. I read some where that most of the root mass is gained during vegging because during flowering all the new growth goes into the buds. IMO it wouldn't be worth it then because the roots have already been established. Root mass is a big factor in how much nutrients the plant can take in (the point of hydro).
Like formula said, if you're already half way through flowering--ride it out. You're in the most important part of the grow, and you want to risk shocking/stressing or even killing the plant by changing it's medium? Just smoke a joint and think how good your last soil grown ganja will be in another 4 weeks or so. Assuming you're switiching to hydro next...
Ya thats a pretty wild idea. Not a dumb one, just kinda crazy. Itd be interesting to see what would happen if u switched the medium at 12/12....but it still would stress the helll out of your plant. thats kinda like moving to the moon when your 10