Actually transport systems are not entirely halted, need of water during cloning, or flowers in water are proof of that.. I'd say they're more than signifigantly diminished though, and I agree that the increased 'breakdowns' mentioned are a major factor..
can.i.buz has a point, I HATE trimming limp weed.. I always soaked them just prior to chopping, and trimmed them immediately after the cut.. The majority sat in wet darkness for a while since I don't trim very quickly, and I had about 2kg/crop.. My hands were usually so cramped when I was done that I was essentially crippled for a few days..