Chris, I have a feeling of de ja vu with you on this subject:
Vitamins and supplements run into trouble with "isolates" ... when you take ONE chemical from a food and turn it into a supplement. ANY vitamin needs other vitamins, minerals, factors and co-factors for total assimilation in the body. If they aren't readily available in from a food source, the liver wil tract down what it's stored away and leach it for use. Smart liver, eh? BUT, what do you have when it's leaching something that's being "used" elsewhere?
A mega dose of isolated vitamin C mostly goes down the toilet. Vitamin C from a wholefood has all that it needs to be imediately recognized and put into use by the liver. For me, this is a no-brainer.